Almost universally when I see people (EDIT: people in this forum using Unity3D) reaching for multithreading or multitasking, this is what happened:
- I have a game idea
- I tried a simple brute force implementation
- oh my gosh it is unbelievably slow on mobile
- go to the internet and google
- read “multithreading can make programs faster!”
Now people go to their Unity project with this one giant multitasking hammer they found and start smashing everything flat with it, making everything multithreaded and multitasked and doing all this crazy complicated work, obfuscating the original flow of their program, almost always introducing new bugs, new edge cases and complicated use requirements.
Finally they test it on the actual hardware. It didn’t get any faster.
But their tech debt sure went up! What used to be simple in their project (“spawn a creature!”) has become a multithreaded process of firing up a task, creating, configuring and injecting a creature specification object, sending it off to run on the creature-making thread, then hooking it back in using some kind of delegate marshaling scheme… and…
The game is still slow.
Well, turns out that the game was originally slow because they were pushing too many pixels, not because they were running everything on the main thread.
Again, I stand by what I said above:
ALSO:
For all performance and optimization issues, ALWAYS start by using the Profiler window:
Window → Analysis → Profiler
DO NOT OPTIMIZE “JUST BECAUSE…” If you don’t have a problem, DO NOT OPTIMIZE!
If you DO have a problem, there is only ONE way to find out: measuring with the profiler.
Failure to use the profiler first means you’re just guessing, making a mess of your code for no good reason.
Not only that but performance on platform A will likely be completely different than platform B. Test on the platform(s) that you care about, and test to the extent that it is worth your effort, and no more.
Remember that you are gathering information at this stage. You cannot FIX until you FIND.
Remember that optimized code is ALWAYS harder to work with and more brittle, making subsequent feature development difficult or impossible, or incurring massive technical debt on future development.
Don’t forget about the Frame Debugger window either, available right near the Profiler in the menu system.
Notes on optimizing UnityEngine.UI setups:
At a minimum you want to clearly understand what performance issues you are having:
- running too slowly?
- loading too slowly?
- using too much runtime memory?
- final bundle too large?
- too much network traffic?
- something else?
If you are unable to engage the profiler, then your next solution is gross guessing changes, such as “reimport all textures as 32x32 tiny textures” or “replace some complex 3D objects with cubes/capsules” to try and figure out what is bogging you down.
Each experiment you do may give you intel about what is causing the performance issue that you identified. More importantly let you eliminate candidates for optimization. For instance if you swap out your biggest textures with 32x32 stamps and you STILL have a problem, you may be able to eliminate textures as an issue and move onto something else.
This sort of speculative optimization assumes you’re properly using source control so it takes one click to revert to the way your project was before if there is no improvement, while carefully making notes about what you have tried and more importantly what results it has had.
“Software does not run in a magic fairy aether powered by the fevered dreams of CS PhDs.” - Mike Acton