I have a similar or even worse experience so far.
I opted out of SU4beta for this build. While it is generally similiar in performance to SU3 for me, it introduces a lot of nasty bugs and regressions. Quite a few of those with 3rd party add-ons which I use exclusively.
Just to name a few most annoying ones for me:
- Camera switching reloads textured every time
- General loading of textures is way slower
- Strange highlighting of options in all menu lists
- Some of my favorite 3rd party planes and airports are bugged
- no restart of flight possible
- ground textures are randomly broken on airports
- strange temporary hammering of main thread which leads to a stutterfest when airborne
Will be back for the next build.