I'll lend some support to the complaints - V3 is just so much slower than V2, nevermind V1, and it's using a lot more system resources now. It seems that lumping everything into one app has bloated it out in just the same way that Adobe's stuff got bloated, and it's sad to see Affinity drift in that direction as well.

I have all 3 versions installed, but most of the time I reach for Affinity Photo V1 just because it will launch faster. If I need Designer, I reach for Affinity Designer V2.