Performance: opening the toolbox

[rachel-fenichel]

Switching toolbox categories takes far longer than it ought to, given that we have a mostly static set of blocks. This isn't really surprising since we've never tried to optimize that code.

Some ideas and potential low hanging fruit:

• Better caching of computed text length for strings
• Avoid spurious rerendering of fields
• For fully static categories, cache block coordinates instead of needing a layout pass
  • This might not actually be an improvement; I need to look into it.

[thisandagain]

@rachel-fenichel and @picklesrus is this something you folks could help us with?

[rachel-fenichel]

Yes, it's something that I'm thinking about but don't have any patches yet.

[picklesrus]

Yeah, as @rachel-fenichel mentioned, we haven't tried to optimize it and there is likely lots of low hanging fruit. It might be a while til I could look at this in depth, but I'll try and keep it top of mind. Here's one thing I noticed while in the code today:

Flyout's getMetrics calls getBBox() on the block canvas which, iirc, causes a layout pass. We should be able to replace that with something like getBlocksBoundingBox which uses cached blocks sizes. I haven't looked into how often we call Flyout's getMetrics though so it might just be a minor win.