CPU Perf Issues (pointclouds)

[loshjawrence]

Just documenting current CPU perf issues in cesium (pointclouds).

Built with combineRelease.

Biggest and most consistent bottleneck: loading the whole payload when it comes back. Already on a promise so maybe not such a big deal (not blocking main thread, not leading to camera stutter on flight)

Thinner call stacks are the normal render, wider call stacks are the payload loading (zoomed out of above)

Not as common but a few of these (bufferData from createVertexBuffer)

Non-image related issues mentioned in #7400 affect pointclouds as well.

One additional thing that seems unique to pointclouds is View.createPotentiallyVisibleTileset. (Or at least noticeable relative to its typical render time). Consistently around 5ms. Related to many calls to ShaderCache.getDerivedShaderProgram

[loshjawrence]

While not cpu perf, @OmarShehata pointed this out to me which might be useful for pointcloud fps since it is quite low (< 20) at times.
https://charto.net/blog/drawing-points-properly-in-webgl/

While I'm mentioning pointcloud fps, overdraw is an issue.

more precisely size points would help, front to back tile rending with the aid of a stencil would help.