Perform regexp compile at package level

Author: cmaglie

arduino/cores/packagemanager/loader.go

@@ -22,6 +22,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/arduino/arduino-cli/arduino/cores"
 	"github.com/arduino/arduino-cli/arduino/discovery"
@@ -420,6 +421,9 @@ func convertLegacyPlatformToPluggableDiscovery(platform *cores.PlatformRelease)
 	}
 }
 
+var netPropRegexp = regexp.MustCompile(`\{upload\.network\.([^}]+)\}`)
+var netPropRegexpMutex sync.Mutex
+
 func convertLegacyNetworkPatternToPluggableDiscovery(props *properties.Map, newToolName string) *properties.Map {
 	pattern, ok := props.GetOk("upload.network_pattern")
 	if !ok {
@@ -434,11 +438,12 @@ func convertLegacyNetworkPatternToPluggableDiscovery(props *properties.Map, newT
 		pattern = strings.ReplaceAll(pattern, "{network.password}", "{upload.field.password}")
 	}
 	// Search for "{upload.network.PROPERTY}"" and convert it to "{upload.port.property.PROPERTY}"
-	netPropRegexp := regexp.MustCompile(`\{upload\.network\.([^}]+)\}`)
+	netPropRegexpMutex.Lock()
 	for netPropRegexp.MatchString(pattern) {
 		netProp := netPropRegexp.FindStringSubmatch(pattern)[1]
 		pattern = strings.ReplaceAll(pattern, "{upload.network."+netProp+"}", "{upload.port.properties."+netProp+"}")
 	}
+	netPropRegexpMutex.Unlock()
 	props.Set("upload.pattern", pattern)
 
 	prefix := "tools." + newToolName + "."