I don't mind the changes for 3.0. Not at all. I can work with the costume editor, the new blocks, pretty much everything that's complained about.

But, unfortunately, the sound editor is horrible for me to work with. First of all, if a song is too long, you can't add any effects to it. You can't even crop the song so that it's shorter. You have to do that all with an outside editor, which often cost money if you want one that actually works.
Solution: Don't have the length of the song influence if you can make it louder, quieter, faster, slower, or croppable. Or, even better, bring back the cropping system from before. I don't know if storage issues or something like that is the reason, but if not, I really wish it would be improved.

Next is the lag. It's impossible to work with.

Let's say you have a rythm-based game that requires you to do things along with the music (like a Rythm Heaven clone). Those projects don't work, because if you have a “Wait __ seconds” block, it waits it out, but if that block is supposed to be with the music precisely, it might freeze and ruin the whole project. It also makes smooth animations on a sprite look bad. It wouldn't be as major if it was only when editing projects. But it also happens when viewing a project. You can't even move your mouse around for too long or else LAG.
Solution: Anything, anything that can reduce or stop the lag. It's nearly unbearable.

I agree

Me too I dislike the lag.

Same, I have that problem too, for some reason the slowing down button doesn't seem to work on longer pieces of audio. As for the lag, that is an easy fix, you can simply use Turbowarp.

everytime I play a sound then reopen the sound. I see and hear that it gets softer. HELP MEH