Investigate frontend performance

[kazcw]

Profile these objectives:

• Startup
• Opening the Component Browser
• Opening a drop-down

Identify areas for performance improvement.

[jdunkerley]

This purely on the IDE side - Jaroslav has done work on the project manager side already.

[kazcw]

Findings

Startup:

• Time taken: 6s of frontend CPU time; 9.2s waiting for backend.
• 23% of CPU time is spent in redraw_line (Issue: Optimize text rendering #5669).
• 23% of CPU time is spent parsing documentation (Issue: Generate HTML docs from Rust documentation AST #5670).

Opening a dropdown (6 short lines):

• Time taken: 450ms.
• 99% of CPU time is in redraw_line (20-100ms/call)
• Grid view's set_model requires 2 redraw_line calls per line (Issue: Optimize text rendering during dropdown grid view creation #5671).

Opening component browser:

• Time taken: 1.7s
• Most time spent in redraw_line.
• No other obvious room for improvement; many small costs that add up. FRP overhead may be a significant contributor.

[enso-bot]

Keziah Wesley reports a new STANDUP for today (2023-02-15):

Progress: Profiled the frontend. It should be finished by 2023-02-15.

Next Day: Next day I will be working on the #5669 task. Investigate performance of text rendering, as it's the most likely area for big frontend optimizations.

[wdanilo]

@kazcw thanks again for such a clear breakdown of your findings, very helpful!

Few questions:

1. I understand that the parsing is really JS problem and after moving to our new parser (when it will support docs parsing) this should be resolved, right?
2. The redraw_lines case is interesting. I've written a comment about it in another issue. We need to investigate it further, as if this is connected to MSDF calls, we are probably doing something wrong there.