diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/020-io-error-6144.diff b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/020-io-error-6144.diff
new file mode 100644
index 000000000..14c1cff5f
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/020-io-error-6144.diff
@@ -0,0 +1,13 @@
+diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+index 4b9db94..c44dea6 100644
+--- a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
++++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+@@ -2,7 +2,7 @@ extern crate futures;
+
+ use futures::{Future, Poll};
+
+-const BUFFER_SIZE: usize = 1;
++const BUFFER_SIZE: usize = 6144;
+ pub struct Error(::std::io::Error);
+
+ struct Dummy<T>(T);
diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/030-u32-3072.diff b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/030-u32-3072.diff
new file mode 100644
index 000000000..f361c8124
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/030-u32-3072.diff
@@ -0,0 +1,15 @@
+diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+index c44dea6..b555f05 100644
+--- a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
++++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+@@ -2,8 +2,8 @@ extern crate futures;
+
+ use futures::{Future, Poll};
+
+-const BUFFER_SIZE: usize = 6144;
+-pub struct Error(::std::io::Error);
++const BUFFER_SIZE: usize = 3072;
++pub struct Error(u32);
+
+ struct Dummy<T>(T);
+ impl<T> Future for Dummy<T> {
diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/031-u8-3072.diff b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/031-u8-3072.diff
new file mode 100644
index 000000000..09e97c4d6
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/031-u8-3072.diff
@@ -0,0 +1,13 @@
+diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+index f8f91d6..b555f05 100644
+--- a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
++++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+@@ -3,7 +3,7 @@ extern crate futures;
+ use futures::{Future, Poll};
+
+ const BUFFER_SIZE: usize = 3072;
+-pub struct Error(u32);
++pub struct Error(u8);
+
+ struct Dummy<T>(T);
+ impl<T> Future for Dummy<T> {
diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/040-empty-3072.diff b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/040-empty-3072.diff
new file mode 100644
index 000000000..40370390a
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/040-empty-3072.diff
@@ -0,0 +1,13 @@
+diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+index f8f91d6..72382a0 100644
+--- a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
++++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+@@ -3,7 +3,7 @@ extern crate futures;
+ use futures::{Future, Poll};
+
+ const BUFFER_SIZE: usize = 3072;
+-pub struct Error(u8);
++pub struct Error;
+
+ struct Dummy<T>(T);
+ impl<T> Future for Dummy<T> {
diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/050-static-str-6144.diff b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/050-static-str-6144.diff
new file mode 100644
index 000000000..ad7ac00e4
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/050-static-str-6144.diff
@@ -0,0 +1,15 @@
+diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+index 72382a0..5d8fc67 100644
+--- a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
++++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
+@@ -2,8 +2,8 @@ extern crate futures;
+
+ use futures::{Future, Poll};
+
+-const BUFFER_SIZE: usize = 3072;
+-pub struct Error;
++const BUFFER_SIZE: usize = 6144;
++pub struct Error(&'static str);
+
+ struct Dummy<T>(T);
+ impl<T> Future for Dummy<T> {
diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Cargo.lock b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Cargo.lock
new file mode 100644
index 000000000..e3f5bbe94
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Cargo.lock
@@ -0,0 +1,14 @@
+[[package]]
+name = "futures"
+version = "0.1.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "issue-46649-byte-filling-slowing-down-sroa"
+version = "0.1.0"
+dependencies = [
+ "futures 0.1.17 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[metadata]
+"checksum futures 0.1.17 (registry+https://github.com/rust-lang/crates.io-index)" = "118b49cac82e04121117cbd3121ede3147e885627d82c4546b87c702debb90c1"
diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Cargo.toml b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Cargo.toml
new file mode 100644
index 000000000..a6cadf023
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "issue-46649-byte-filling-slowing-down-sroa"
+version = "0.1.0"
+
+[dependencies]
+futures = "=0.1.17"
diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Makefile b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Makefile
new file mode 100644
index 000000000..e1fdb4266
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/Makefile
@@ -0,0 +1,46 @@
+.PHONY: all@010-prepare \
+		patches
+
+# Make the depedencies available. Should finish very quickly.
+all@010-prepare:
+	$(CARGO) rustc --release $(CARGO_OPTS) -- $(CARGO_RUSTC_OPTS)
+
+# Set length to 6144 using std::io::Error as error.
+# Fast (~1s) on 1.22.1, Slow (~16s) on 1.23.0-beta.2.
+all@020-io-error-6144:
+	patch -Np4 -i 020-io-error-6144.diff
+	$(CARGO) rustc --release $(CARGO_OPTS) -- $(CARGO_RUSTC_OPTS)
+
+# Change error type to u32, reduce length to 3072 to avoid taking too long time.
+# Slow (~21s) on 1.22.1, Fast (~1s) on 1.23.0-beta.2.
+all@030-u32-3072:
+	patch -Np4 -i 030-u32-3072.diff
+	$(CARGO) rustc --release $(CARGO_OPTS) -- $(CARGO_RUSTC_OPTS)
+
+# Change error type to u8.
+# Slow (~21s) on 1.22.1, Fast (~1s) on 1.23.0-beta.2.
+all@031-u8-3072:
+	patch -Np4 -i 031-u8-3072.diff
+	$(CARGO) rustc --release $(CARGO_OPTS) -- $(CARGO_RUSTC_OPTS)
+
+# Change error type to empty.
+# Slow (~20s) on 1.22.1, Very slow (~27s) on 1.23.0-beta.2.
+all@040-empty-3072:
+	patch -Np4 -i 040-empty-3072.diff
+	$(CARGO) rustc --release $(CARGO_OPTS) -- $(CARGO_RUSTC_OPTS)
+
+# Change error type to &str, increase length back to 6144 as this one is faster.
+# Slow (~22s) on 1.22.1, Medium (~8s) on 1.23.0-beta.2.
+all@050-static-str-6144:
+	patch -Np4 -i 050-static-str-6144.diff
+	$(CARGO) rustc --release $(CARGO_OPTS) -- $(CARGO_RUSTC_OPTS)
+
+patches:
+	@echo "\
+		@010-prepare \
+		@020-io-error-6144 \
+		@030-u32-3072 \
+		@031-u8-3072 \
+		@040-empty-3072 \
+		@050-static-str-6144 \
+	"
diff --git a/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
new file mode 100644
index 000000000..435ded8f6
--- /dev/null
+++ b/collector/benchmarks/issue-46449-byte-filling-slowing-down-sroa/src/lib.rs
@@ -0,0 +1,24 @@
+extern crate futures;
+
+use futures::{Future, Poll};
+
+const BUFFER_SIZE: usize = 1;
+pub struct Error(::std::io::Error);
+
+struct Dummy<T>(T);
+impl<T> Future for Dummy<T> {
+    type Item = T;
+    type Error = Error;
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+        loop {}
+    }
+}
+
+pub fn run() -> Box<Future<Item = (), Error = Error>> {
+    let c2s = Dummy([0u8; BUFFER_SIZE]).then(move |_| Ok(0));
+    let s2c = Dummy(()).then(move |_| Ok(0));
+    let fut = c2s.select(s2c)
+        .and_then(move |_| Ok(()))
+        .map_err(|(err, _)| err);
+    Box::new(fut)
+}
diff --git a/collector/check-benchmarks.sh b/collector/check-benchmarks.sh
index 7ac542c35..e4be80a96 100755
--- a/collector/check-benchmarks.sh
+++ b/collector/check-benchmarks.sh
@@ -18,6 +18,7 @@ for dir in *; do
             start_time=$(date -u '+%s%N')
             CARGO=cargo \
             RUSTC=rustc \
+            CARGO_RUSTC_OPTS=--cap-lints=warn \
             make "all$patch";
             end_time=$(date -u '+%s%N')
             duration=$(($end_time-$start_time))