Noticeable delay on startup

[hannobraun]

Since egui support was merged (#763), I'm seeing a noticeable delay on startup. The window opens immediately, but stays transparent for some time, maybe half a second. After that, the UI and graphics are shown like normal, and I notice no other problems.

This is on an AMD Ryzen 7 5700G with Radeon Graphics (is what lshw says). Maybe it's related to #807.

[jeevcat]

The main delay at startup that I'm seeing is waiting for cargo build of the model to finish. Would be nice if this was somehow non-blocking.

[hannobraun]

The main delay at startup that I'm seeing is waiting for cargo build of the model to finish.

I haven't timed what the main delay is on my machine, but there's definitely something different since egui support was merged.

Would be nice if this was somehow non-blocking.

Yes, definitely. I think right now, all the code assumes that a model is always loaded. Would be nicer, if that were not the case. Then we could load the model asynchronously, and also support starting Fornjot without a model loaded, and then load that through in-app UI. (That second one is not important right now, I think. But it would be nice to support that, even if just as a capability that alternate Fornjot-based apps could use.)

[hannobraun]

I haven't seen any exceptional delays in a while, except when the model took longer to compile for some reason. That might have been the source of the delay in the first place (as @jeevcat noted), or maybe I was seeing something weird that has since cleared up (we have updated relevant dependencies multiple times since then).

I've also opened #1015 to track the specific problem of the GUI not showing before the model is loaded. Closing in favor of that.