Fsharp: Slow down in Visual Studio Preview with Package references for F# scripts

[toburger]

The editor of Visual Studio Preview gets extremely (at this stage unusable) slow after referencing a NuGet package in a F# script file.

Repro steps

Provide the steps required to reproduce the problem:

1. Enable preview language features:
   

2. Reference a NuGet package, e.g. #r "nuget: ML"

3. Certain actions cause the editor to slow down very noticeably (hit enter, wait for the auto completion list)

Expected behavior

Actual behavior

It's hard to tell from the screen capture, but I deliberately typed very slow to wait for the auto completion to kick in...

Related information

• Windows 10 Insider; Version 2004 (Build 19041.153)
• .NET 5 Preview
• Microsoft Visual Studio Preview Community
• Surface Laptop Gen1 i5

[cartermp]

Thanks for the report @toburger. We'll need to make sure the IDE support is in good shape before going live with F# 5. Right now we've only been focused on getting the core mechanism right, so IDE support will likely follow in the next set of previews.

[MaxWilson]

This issue was driving me mad because I love the feature but the perf issue blocks the UI and prevents me from typing for 1-3 seconds after almost every time I type anything, but fortunately I found a workaround: if I comment out the nuget reference the issue goes away.

An alternate workaround that I tried was to enable Options | F# | Intellisense | "Enable stale data for Intellisense features" and turn the time down to 10 ms, but that did not help.

I'm on Visual Studio Version 16.6.0 Preview 6.0

[jonsagara]

Hi, is this scheduled to be fixed before the full release of VS 16.8.0?

[cartermp]

We would like to get this resolved by VS 16.8, yes. @KevinRansom was looking into this before a more urgent bug arose.

[cartermp]

This is unlikely to get resolved by 16.8. Sorry. The feature is not ready for use within VS. Moving out.