diff --git a/src/FsAutoComplete.Core/AdaptiveExtensions.fs b/src/FsAutoComplete.Core/AdaptiveExtensions.fs
index b87a0a97a..1b5c4b7eb 100644
--- a/src/FsAutoComplete.Core/AdaptiveExtensions.fs
+++ b/src/FsAutoComplete.Core/AdaptiveExtensions.fs
@@ -408,7 +408,7 @@ and AdaptiveCancellableTask<'a>(cancel: unit -> unit, real: Task<'a>) =
       if real.IsCompleted then
         real
       else
-        cachedTcs <- new TaskCompletionSource<'a>()
+        cachedTcs <- new TaskCompletionSource<'a>(TaskCreationOptions.RunContinuationsAsynchronously)
 
         cachedTcs.TrySetFromTaskFinished real
 
diff --git a/src/FsAutoComplete.Core/CompilerServiceInterface.fs b/src/FsAutoComplete.Core/CompilerServiceInterface.fs
index 50322a88e..1db80509c 100644
--- a/src/FsAutoComplete.Core/CompilerServiceInterface.fs
+++ b/src/FsAutoComplete.Core/CompilerServiceInterface.fs
@@ -78,9 +78,22 @@ type CompilerProjectOption =
     | BackgroundCompiler(options) -> options.OtherOptions |> Array.toList
     | TransparentCompiler(snapshot) -> snapshot.OtherOptions
 
-type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize, parallelReferenceResolution, useTransparentCompiler)
-  =
+type FSharpCompilerServiceChecker
+  (
+    hasAnalyzers,
+    typecheckCacheSize,
+    parallelReferenceResolution,
+    useTransparentCompiler,
+    ?transparentCompilerCacheSizes: int
+  ) =
   let checker =
+    let cacheSize =
+      if useTransparentCompiler then
+        TransparentCompiler.CacheSizes.Create(defaultArg transparentCompilerCacheSizes 10)
+        |> Some
+      else
+        None
+
     FSharpChecker.Create(
       projectCacheSize = 200,
       keepAssemblyContents = hasAnalyzers,
@@ -91,7 +104,8 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize, parallelRefe
       enablePartialTypeChecking = not hasAnalyzers,
       parallelReferenceResolution = parallelReferenceResolution,
       captureIdentifiersWhenParsing = true,
-      useTransparentCompiler = useTransparentCompiler
+      useTransparentCompiler = useTransparentCompiler,
+      ?transparentCompilerCacheSizes = cacheSize
     )
 
   let entityCache = EntityCache()
@@ -502,7 +516,10 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize, parallelRefe
             let ops =
               MemoryCacheEntryOptions().SetSize(1).SetSlidingExpiration(TimeSpan.FromMinutes(5.))
 
-            return lastCheckResults.Set(filePath, r, ops)
+            lastCheckResults.Set(filePath, WeakReference<ParseAndCheckResults>(r), ops)
+            |> ignore<WeakReference<ParseAndCheckResults>>
+
+            return r
           else
             return r
       with ex ->
@@ -553,7 +570,10 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize, parallelRefe
             let ops =
               MemoryCacheEntryOptions().SetSize(1).SetSlidingExpiration(TimeSpan.FromMinutes(5.))
 
-            return lastCheckResults.Set(filePath, r, ops)
+            lastCheckResults.Set(filePath, WeakReference<ParseAndCheckResults>(r), ops)
+            |> ignore<WeakReference<ParseAndCheckResults>>
+
+            return r
           else
             return r
       with ex ->
@@ -578,8 +598,11 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize, parallelRefe
 
     checkerLogger.info (Log.setMessage "{opName}" >> Log.addContextDestructured "opName" opName)
 
-    match lastCheckResults.TryGetValue<ParseAndCheckResults>(file) with
-    | (true, v) -> Some v
+    match lastCheckResults.TryGetValue<WeakReference<ParseAndCheckResults>>(file) with
+    | (true, v) ->
+      match v.TryGetTarget() with
+      | (true, v) -> Some v
+      | _ -> None
     | _ -> None
 
   member _.TryGetRecentCheckResultsForFile(file: string<LocalPath>, snapshot: FSharpProjectSnapshot) =
diff --git a/src/FsAutoComplete.Core/CompilerServiceInterface.fsi b/src/FsAutoComplete.Core/CompilerServiceInterface.fsi
index bb953853c..dce6fbf5a 100644
--- a/src/FsAutoComplete.Core/CompilerServiceInterface.fsi
+++ b/src/FsAutoComplete.Core/CompilerServiceInterface.fsi
@@ -29,7 +29,11 @@ type CompilerProjectOption =
 
 type FSharpCompilerServiceChecker =
   new:
-    hasAnalyzers: bool * typecheckCacheSize: int64 * parallelReferenceResolution: bool * useTransparentCompiler: bool ->
+    hasAnalyzers: bool *
+    typecheckCacheSize: int64 *
+    parallelReferenceResolution: bool *
+    useTransparentCompiler: bool *
+    ?transparentCompilerCacheSizes: int ->
       FSharpCompilerServiceChecker
 
   member DisableInMemoryProjectReferences: bool with get, set
diff --git a/src/FsAutoComplete.Core/Utils.fs b/src/FsAutoComplete.Core/Utils.fs
index 31c58f3a9..342a67641 100644
--- a/src/FsAutoComplete.Core/Utils.fs
+++ b/src/FsAutoComplete.Core/Utils.fs
@@ -70,7 +70,9 @@ module ProcessHelper =
 
   let WaitForExitAsync (p: Process) =
     asyncEx {
-      let tcs = TaskCompletionSource<obj>()
+      let tcs =
+        TaskCompletionSource<obj>(TaskCreationOptions.RunContinuationsAsynchronously)
+
       p.EnableRaisingEvents <- true
       p.Exited.Add(fun _args -> tcs.TrySetResult(null) |> ignore)
 
diff --git a/src/FsAutoComplete/LspHelpers.fs b/src/FsAutoComplete/LspHelpers.fs
index 6db940947..e333cef85 100644
--- a/src/FsAutoComplete/LspHelpers.fs
+++ b/src/FsAutoComplete/LspHelpers.fs
@@ -86,11 +86,7 @@ module Conversions =
       | Some(U2.C2 code) -> code |> Some
       | None -> None
 
-  type TextDocumentIdentifier with
-
-    member doc.GetFilePath() = Path.FileUriToLocalPath doc.Uri
-
-  type VersionedTextDocumentIdentifier with
+  type ITextDocumentIdentifier with
 
     member doc.GetFilePath() = Path.FileUriToLocalPath doc.Uri
 
diff --git a/src/FsAutoComplete/LspHelpers.fsi b/src/FsAutoComplete/LspHelpers.fsi
index 857c93fb7..8848a41db 100644
--- a/src/FsAutoComplete/LspHelpers.fsi
+++ b/src/FsAutoComplete/LspHelpers.fsi
@@ -46,11 +46,7 @@ module Conversions =
 
     member CodeAsString: string option
 
-  type TextDocumentIdentifier with
-
-    member GetFilePath: unit -> string
-
-  type VersionedTextDocumentIdentifier with
+  type ITextDocumentIdentifier with
 
     member GetFilePath: unit -> string
 
diff --git a/src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs b/src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs
index 092ee01ab..4a4c5eb9a 100644
--- a/src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs
+++ b/src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs
@@ -939,7 +939,7 @@ type AdaptiveFSharpLspServer
           let (filePath, pos) = getFilePathAndPosition p
           let! volatileFile = state.GetOpenFileOrRead filePath |> AsyncResult.ofStringErr
           let! lineStr = volatileFile.Source |> tryGetLineStr pos |> Result.lineLookupErr
-          and! tyRes = state.GetOpenFileTypeCheckResultsCached filePath |> AsyncResult.ofStringErr
+          and! tyRes = state.GetOpenFileTypeCheckResults filePath |> AsyncResult.ofStringErr
 
           match tyRes.TryGetToolTipEnhanced pos lineStr with
           | Some tooltipResult ->
@@ -1580,7 +1580,7 @@ type AdaptiveFSharpLspServer
           let filePath = Path.FileUriToLocalPath data.[0] |> Utils.normalizePath
 
           try
-            let! tyRes = state.GetOpenFileTypeCheckResultsCached filePath |> AsyncResult.ofStringErr
+            let! tyRes = state.GetOpenFileTypeCheckResults filePath |> AsyncResult.ofStringErr
 
 
             logger.info (
diff --git a/src/FsAutoComplete/LspServers/AdaptiveServerState.fs b/src/FsAutoComplete/LspServers/AdaptiveServerState.fs
index 31f231250..d4aa44cac 100644
--- a/src/FsAutoComplete/LspServers/AdaptiveServerState.fs
+++ b/src/FsAutoComplete/LspServers/AdaptiveServerState.fs
@@ -377,6 +377,14 @@ type AdaptiveState
     disposables.Add
     <| fileParsed.Publish.Subscribe(fun (parseResults, proj, ct) -> detectTests parseResults proj ct)
 
+  let analyzersLocker = new SemaphoreSlim(1, 1)
+
+  let typecheckLocker =
+    let maxConcurrency =
+      Math.Max(1.0, Math.Floor(float System.Environment.ProcessorCount * 0.75)) |> int
+
+    new SemaphoreSlim(maxConcurrency, maxConcurrency)
+
   let builtInCompilerAnalyzers config (file: VolatileFile) (tyRes: ParseAndCheckResults) =
     let filePath = file.FileName
     let filePathUntag = UMX.untag filePath
@@ -390,6 +398,8 @@ type AdaptiveState
     let checkUnusedOpens =
       asyncEx {
         try
+          let! ct = Async.CancellationToken
+          use! _l = analyzersLocker.LockAsync(ct)
           use progress = progressLookup.CreateProgressReport(lspClient, cancellable = true)
           do! progress.Begin($"Checking unused opens {fileName}...", message = filePathUntag)
 
@@ -397,7 +407,6 @@ type AdaptiveState
             UnusedOpens.getUnusedOpens (tyRes.GetCheckResults, getSourceLine)
             |> Async.withCancellation progress.CancellationToken
 
-          let! ct = Async.CancellationToken
           notifications.Trigger(NotificationEvent.UnusedOpens(filePath, (unused |> List.toArray), file.Version), ct)
         with e ->
           logger.error (Log.setMessage "checkUnusedOpens failed" >> Log.addExn e)
@@ -406,6 +415,8 @@ type AdaptiveState
     let checkUnusedDeclarations =
       asyncEx {
         try
+          let! ct = Async.CancellationToken
+          use! _l = analyzersLocker.LockAsync(ct)
           use progress = progressLookup.CreateProgressReport(lspClient, cancellable = true)
           do! progress.Begin($"Checking unused declarations {fileName}...", message = filePathUntag)
 
@@ -417,7 +428,6 @@ type AdaptiveState
 
           let unused = unused |> Seq.toArray
 
-          let! ct = Async.CancellationToken
           notifications.Trigger(NotificationEvent.UnusedDeclarations(filePath, unused, file.Version), ct)
         with e ->
           logger.error (Log.setMessage "checkUnusedDeclarations failed" >> Log.addExn e)
@@ -426,6 +436,8 @@ type AdaptiveState
     let checkSimplifiedNames =
       asyncEx {
         try
+          let! ct = Async.CancellationToken
+          use! _l = analyzersLocker.LockAsync(ct)
           use progress = progressLookup.CreateProgressReport(lspClient, cancellable = true)
           do! progress.Begin($"Checking simplifying of names {fileName}...", message = filePathUntag)
 
@@ -434,7 +446,6 @@ type AdaptiveState
             |> Async.withCancellation progress.CancellationToken
 
           let simplified = Array.ofSeq simplified
-          let! ct = Async.CancellationToken
           notifications.Trigger(NotificationEvent.SimplifyNames(filePath, simplified, file.Version), ct)
         with e ->
           logger.error (Log.setMessage "checkSimplifiedNames failed" >> Log.addExn e)
@@ -443,6 +454,8 @@ type AdaptiveState
     let checkUnnecessaryParentheses =
       asyncEx {
         try
+          let! ct = Async.CancellationToken
+          use! _l = analyzersLocker.LockAsync(ct)
           use progress = progressLookup.CreateProgressReport(lspClient)
           do! progress.Begin($"Checking for unnecessary parentheses {fileName}...", message = filePathUntag)
 
@@ -464,8 +477,6 @@ type AdaptiveState
 
               | _ -> ranges)
 
-          let! ct = Async.CancellationToken
-
           notifications.Trigger(
             NotificationEvent.UnnecessaryParentheses(filePath, Array.ofSeq unnecessaryParentheses, file.Version),
             ct
@@ -1599,6 +1610,8 @@ type AdaptiveState
 
           ]
 
+      let! ct = Async.CancellationToken
+      use! _l = typecheckLocker.LockAsync ct
       use _ = fsacActivitySource.StartActivityForType(thisType, tags = tags)
 
 
diff --git a/src/FsAutoComplete/LspServers/Common.fs b/src/FsAutoComplete/LspServers/Common.fs
index 89e3e3fca..63a998ccf 100644
--- a/src/FsAutoComplete/LspServers/Common.fs
+++ b/src/FsAutoComplete/LspServers/Common.fs
@@ -158,7 +158,10 @@ module Async =
     asyncEx {
       let! ct2 = Async.CancellationToken
       use cts = CancellationTokenSource.CreateLinkedTokenSource(ct, ct2)
-      let tcs = new TaskCompletionSource<'a>()
+
+      let tcs =
+        new TaskCompletionSource<'a>(TaskCreationOptions.RunContinuationsAsynchronously)
+
       use _reg = cts.Token.Register(fun () -> tcs.TrySetCanceled(cts.Token) |> ignore)
 
       let a =