diff --git a/compiler/src/dotty/tools/dotc/ast/Trees.scala b/compiler/src/dotty/tools/dotc/ast/Trees.scala
index 53b072fdeec8..721bac57d907 100644
--- a/compiler/src/dotty/tools/dotc/ast/Trees.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Trees.scala
@@ -174,7 +174,7 @@ object Trees {
     def toList: List[Tree[T]] = this :: Nil
 
     /** if this tree is the empty tree, the alternative, else this tree */
-    def orElse[U >: Untyped <: T](that: => Tree[U]): Tree[U] =
+    inline def orElse[U >: Untyped <: T](inline that: Tree[U]): Tree[U] =
       if (this eq genericEmptyTree) that else this
 
     /** The number of nodes in this tree */
diff --git a/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala b/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
index 2c3f88c1ce5c..b1d2addfe6af 100644
--- a/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
+++ b/compiler/src/dotty/tools/dotc/config/ScalaSettings.scala
@@ -181,6 +181,7 @@ class ScalaSettings extends Settings.SettingGroup {
   val YnoDecodeStacktraces: Setting[Boolean] = BooleanSetting("-Yno-decode-stacktraces", "Show raw StackOverflow stacktraces, instead of decoding them into triggering operations.")
 
   val Yinstrument: Setting[Boolean] = BooleanSetting("-Yinstrument", "Add instrumentation code that counts allocations and closure creations.")
+  val YinstrumentDefs: Setting[Boolean] = BooleanSetting("-Yinstrument-defs", "Add instrumentation code that counts method calls; needs -Yinstrument to be set, too.")
 
   /** Dottydoc specific settings */
   val siteRoot: Setting[String] = StringSetting(
diff --git a/compiler/src/dotty/tools/dotc/core/Contexts.scala b/compiler/src/dotty/tools/dotc/core/Contexts.scala
index b2258dee613d..179b40a18bb4 100644
--- a/compiler/src/dotty/tools/dotc/core/Contexts.scala
+++ b/compiler/src/dotty/tools/dotc/core/Contexts.scala
@@ -674,7 +674,7 @@ object Contexts {
     final def retractMode(mode: Mode): c.type = c.setMode(c.mode &~ mode)
   }
 
-  private def exploreCtx(using Context): Context =
+  private def exploreCtx(using Context): FreshContext =
     util.Stats.record("explore")
     val base = ctx.base
     import base._
@@ -701,6 +701,10 @@ object Contexts {
     val ectx = exploreCtx
     try op(using ectx) finally wrapUpExplore(ectx)
 
+  inline def exploreInFreshCtx[T](inline op: FreshContext ?=> T)(using Context): T =
+    val ectx = exploreCtx
+    try op(using ectx) finally wrapUpExplore(ectx)
+
   private def changeOwnerCtx(owner: Symbol)(using Context): Context =
     val base = ctx.base
     import base._
diff --git a/compiler/src/dotty/tools/dotc/core/Denotations.scala b/compiler/src/dotty/tools/dotc/core/Denotations.scala
index 73e98461046e..752ab3aaa955 100644
--- a/compiler/src/dotty/tools/dotc/core/Denotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/Denotations.scala
@@ -237,7 +237,7 @@ object Denotations {
     def mapInfo(f: Type => Type)(using Context): Denotation
 
     /** If this denotation does not exist, fallback to alternative */
-    final def orElse(that: => Denotation): Denotation = if (this.exists) this else that
+    inline def orElse(inline that: Denotation): Denotation = if (this.exists) this else that
 
     /** The set of alternative single-denotations making up this denotation */
     final def alternatives: List[SingleDenotation] = altsWith(alwaysTrue)
@@ -596,7 +596,7 @@ object Denotations {
     def mapInfo(f: Type => Type)(using Context): SingleDenotation =
       derivedSingleDenotation(symbol, f(info))
 
-    def orElse(that: => SingleDenotation): SingleDenotation = if (this.exists) this else that
+    inline def orElse(inline that: SingleDenotation): SingleDenotation = if (this.exists) this else that
 
     def altsWith(p: Symbol => Boolean): List[SingleDenotation] =
       if (exists && p(symbol)) this :: Nil else Nil
diff --git a/compiler/src/dotty/tools/dotc/core/Symbols.scala b/compiler/src/dotty/tools/dotc/core/Symbols.scala
index 9b0b42734381..7ba320159531 100644
--- a/compiler/src/dotty/tools/dotc/core/Symbols.scala
+++ b/compiler/src/dotty/tools/dotc/core/Symbols.scala
@@ -239,7 +239,7 @@ object Symbols {
       }
 
     /** This symbol, if it exists, otherwise the result of evaluating `that` */
-    def orElse(that: => Symbol)(using Context): Symbol =
+    inline def orElse(inline that: Symbol)(using Context): Symbol =
       if (this.exists) this else that
 
     /** If this symbol satisfies predicate `p` this symbol, otherwise `NoSymbol` */
diff --git a/compiler/src/dotty/tools/dotc/core/Types.scala b/compiler/src/dotty/tools/dotc/core/Types.scala
index 19800fc635e6..e0feca8c8d1b 100644
--- a/compiler/src/dotty/tools/dotc/core/Types.scala
+++ b/compiler/src/dotty/tools/dotc/core/Types.scala
@@ -793,7 +793,8 @@ object Types {
      */
     final def memberNames(keepOnly: NameFilter, pre: Type = this)(using Context): Set[Name] = this match {
       case tp: ClassInfo =>
-        tp.cls.classDenot.memberNames(keepOnly) filter (keepOnly(pre, _))
+        val names = tp.cls.classDenot.memberNames(keepOnly)
+        if keepOnly.isStable then names else names.filter(keepOnly(pre, _))
       case tp: RefinedType =>
         val ns = tp.parent.memberNames(keepOnly, pre)
         if (keepOnly(pre, tp.refinedName)) ns + tp.refinedName else ns
@@ -5665,6 +5666,11 @@ object Types {
    */
   abstract class NameFilter {
     def apply(pre: Type, name: Name)(using Context): Boolean
+
+    /** Filter does not need to be rechecked with full prefix, if it
+     *  has been already checked for the class denotation of the prefix
+     */
+    def isStable: Boolean
   }
 
   /** A filter for names of abstract types of a given type */
@@ -5674,6 +5680,7 @@ object Types {
         val mbr = pre.nonPrivateMember(name)
         mbr.symbol.is(Deferred) && mbr.info.isInstanceOf[RealTypeBounds]
       }
+    def isStable = false
   }
 
   /** A filter for names of abstract types of a given type */
@@ -5683,12 +5690,14 @@ object Types {
         val mbr = pre.member(name)
         mbr.symbol.isType && !mbr.symbol.isClass
       }
+    def isStable = false
   }
 
   /** A filter for names of deferred term definitions of a given type */
   object abstractTermNameFilter extends NameFilter {
     def apply(pre: Type, name: Name)(using Context): Boolean =
       name.isTermName && pre.nonPrivateMember(name).hasAltWith(_.symbol.is(Deferred))
+    def isStable = false
   }
 
   /** A filter for names of type aliases of a given type */
@@ -5698,19 +5707,23 @@ object Types {
         val mbr = pre.nonPrivateMember(name)
         mbr.symbol.isAliasType
       }
+    def isStable = false
   }
 
   object typeNameFilter extends NameFilter {
     def apply(pre: Type, name: Name)(using Context): Boolean = name.isTypeName
+    def isStable = true
   }
 
   object fieldFilter extends NameFilter {
     def apply(pre: Type, name: Name)(using Context): Boolean =
       name.isTermName && (pre member name).hasAltWith(!_.symbol.is(Method))
+    def isStable = true
   }
 
   object takeAllFilter extends NameFilter {
     def apply(pre: Type, name: Name)(using Context): Boolean = true
+    def isStable = true
   }
 
   object implicitFilter extends NameFilter {
@@ -5719,6 +5732,7 @@ object Types {
      *  no post-filtering is needed.
      */
     def apply(pre: Type, name: Name)(using Context): Boolean = true
+    def isStable = true
   }
 
   // ----- Debug ---------------------------------------------------------
diff --git a/compiler/src/dotty/tools/dotc/interactive/Completion.scala b/compiler/src/dotty/tools/dotc/interactive/Completion.scala
index c5de3024fcd2..4bb1a828d731 100644
--- a/compiler/src/dotty/tools/dotc/interactive/Completion.scala
+++ b/compiler/src/dotty/tools/dotc/interactive/Completion.scala
@@ -323,6 +323,7 @@ object Completion {
     private object completionsFilter extends NameFilter {
       def apply(pre: Type, name: Name)(using Context): Boolean =
         !name.isConstructorName && name.toTermName.info.kind == SimpleNameKind
+      def isStable = true
     }
   }
 
diff --git a/compiler/src/dotty/tools/dotc/parsing/Scanners.scala b/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
index 241319ea6ff7..bdf74623b244 100644
--- a/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
+++ b/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
@@ -565,7 +565,7 @@ object Scanners {
         lastOffset = prev.lastOffset
         lineOffset = prev.lineOffset
       }
-      token match {
+      (token: @switch) match {
         case CASE =>
           lookAhead()
           if (token == CLASS) fuse(CASECLASS)
@@ -601,8 +601,8 @@ object Scanners {
           if colonSyntax then observeColonEOL()
         case RBRACE | RPAREN | RBRACKET =>
           closeIndented()
-        case EOF if !source.maybeIncomplete =>
-          closeIndented()
+        case EOF =>
+          if !source.maybeIncomplete then closeIndented()
         case _ =>
       }
     }
diff --git a/compiler/src/dotty/tools/dotc/transform/Instrumentation.scala b/compiler/src/dotty/tools/dotc/transform/Instrumentation.scala
index b4d2c541f2c5..676cf00e2f46 100644
--- a/compiler/src/dotty/tools/dotc/transform/Instrumentation.scala
+++ b/compiler/src/dotty/tools/dotc/transform/Instrumentation.scala
@@ -74,6 +74,21 @@ class Instrumentation extends MiniPhase { thisPhase =>
   private def ok(using Context) =
     !ctx.owner.ownersIterator.exists(_.name.toString.startsWith("Stats"))
 
+  override def transformDefDef(tree: DefDef)(using Context): Tree =
+    val sym = tree.symbol
+    if ctx.settings.YinstrumentDefs.value
+      && ok
+      && sym.exists
+      && !sym.isOneOf(Synthetic | Artifact)
+    then
+      def icall = record(i"method/${sym.fullName}", tree)
+      def rhs1 = tree.rhs match
+        case rhs @ Block(stats, expr) => cpy.Block(rhs)(icall :: stats, expr)
+        case _: Match | _: If | _: Try | _: Labeled => cpy.Block(tree.rhs)(icall :: Nil, tree.rhs)
+        case rhs => rhs
+      cpy.DefDef(tree)(rhs = rhs1)
+    else tree
+
   override def transformApply(tree: Apply)(using Context): Tree = tree.fun match {
     case Select(nu: New, _) =>
       cpy.Block(tree)(record(i"alloc/${nu.tpe}", tree) :: Nil, tree)
diff --git a/compiler/src/dotty/tools/dotc/transform/SymUtils.scala b/compiler/src/dotty/tools/dotc/transform/SymUtils.scala
index e70f720501fe..9adc11585638 100644
--- a/compiler/src/dotty/tools/dotc/transform/SymUtils.scala
+++ b/compiler/src/dotty/tools/dotc/transform/SymUtils.scala
@@ -22,12 +22,19 @@ object SymUtils {
 
   extension (self: Symbol) {
 
-  /** All traits implemented by a class or trait except for those inherited through the superclass. */
+  /** All traits implemented by a class or trait except for those inherited
+   *  through the superclass. Traits are given in the order they appear in the
+   *  parents clause (which is the reverse of their order in baseClasses)
+   */
   def directlyInheritedTraits(using Context): List[ClassSymbol] = {
     val superCls = self.asClass.superClass
     val baseClasses = self.asClass.baseClasses
     if (baseClasses.isEmpty) Nil
-    else baseClasses.tail.takeWhile(_ ne superCls).reverse
+    else
+      def recur(bcs: List[ClassSymbol], acc: List[ClassSymbol]): List[ClassSymbol] = bcs match
+        case bc :: bcs1 => if bc eq superCls then acc else recur(bcs1, bc :: acc)
+        case nil => acc
+      recur(baseClasses.tail, Nil)
   }
 
   /** All traits implemented by a class, except for those inherited through the superclass.
diff --git a/compiler/src/dotty/tools/dotc/typer/Implicits.scala b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
index 14ece3c6c594..d52e672f1cee 100644
--- a/compiler/src/dotty/tools/dotc/typer/Implicits.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
@@ -245,10 +245,12 @@ object Implicits:
       if refs.isEmpty && (!considerExtension || companionRefs.isEmpty) then
         Nil
       else
-        val nestedCtx = ctx.fresh.addMode(Mode.TypevarsMissContext)
         val candidates = new mutable.ListBuffer[Candidate]
         def tryCandidate(extensionOnly: Boolean)(ref: ImplicitRef) =
-          var ckind = explore(candidateKind(ref.underlyingRef))(using nestedCtx)
+          var ckind = exploreInFreshCtx { (using ctx: FreshContext) =>
+            ctx.setMode(ctx.mode | Mode.TypevarsMissContext)
+            candidateKind(ref.underlyingRef)
+          }
           if extensionOnly then ckind &= Candidate.Extension
           if ckind != Candidate.None then
             candidates += Candidate(ref, ckind, level)
diff --git a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
index d09dad5ca063..1a6fca704e7d 100644
--- a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -29,6 +29,7 @@ object RefChecks {
 
   private val defaultMethodFilter = new NameFilter {
     def apply(pre: Type, name: Name)(using Context): Boolean = name.is(DefaultGetterName)
+    def isStable = true
   }
 
   /** Only one overloaded alternative is allowed to define default arguments */
@@ -490,10 +491,9 @@ object RefChecks {
        */
       def missingTermSymbols: List[Symbol] =
         val buf = new mutable.ListBuffer[Symbol]
-        for bc <- clazz.baseClasses
-            sym <- bc.info.decls.toList
-            if sym.is(DeferredTerm) && !isImplemented(sym) && !ignoreDeferred(sym)
-        do buf += sym
+        for bc <- clazz.baseClasses; sym <- bc.info.decls.toList do
+          if sym.is(DeferredTerm) && !isImplemented(sym) && !ignoreDeferred(sym) then
+            buf += sym
         buf.toList
 
       // 2. Check that only abstract classes have deferred members