I once spoke with a Canonical Sales guy and he asked me why i said that snaps were not good in the conversation we had prior.
Somehow nobody at canonical thinks that snap performance is an issue at all, he was genuinely surprised. Snap is just unusable, full stop. If everything takes like 10x to open i can not work with my system anymore. I'd rather work with windows or a chalkboard instead.
I don't know who you talked to, but I can tell the story is richer and more interesting than that. Saying that snaps have performance issues is similar to saying that containers have performance issues. They do affect performance because doing something is always more expensive than doing nothing, and snaps do something in addition to just running a bare executable on your machine. At the same time, the kind of operation that snaps perform should not have a significant impact on a modern computer to the point of making it slow or annoying, because most of the operations are relatively simple and happen at a low level, and computers are fast.
At the same time, snaps are a new packaging format, and when you change the layout of applications to include things such as restrictions or making things read-only, suddenly all kinds of things can go wrong, and some of these can cause major performance impact.
Two easy and real examples from the snap world: early on there was a bug where .pyc files would be out of date, and the filesystem was read-only. This meant every single time the application was opened Python would recompile the entire application and fail to write its cache files in every case. Major performance impact. That was fixed.
Another one: fontconfig cache changed its format, and as a side effect applications running could not make use of the one in the system and had to rebuild their own copy every time. Extreme performance impact. That was fixed.
And the list goes on. So the point is: snaps are not slow, because there's nothing fundamental happening there to make them slow. But snap applications can be slow, of course, potentially by orders of magnitude. These are bugs, and we fix them when we see them.
In my experience everything i opened had significantly longer startup times - especially for VS Code this was a problem for me. I can not explain why, i just experienced the symptoms as did a few other people i talked to.
So if it is just an app problem great, hopefully there will be a day when not every app with UI i try has that problem.
Somehow nobody at canonical thinks that snap performance is an issue at all, he was genuinely surprised. Snap is just unusable, full stop. If everything takes like 10x to open i can not work with my system anymore. I'd rather work with windows or a chalkboard instead.