Lasso selection pixels content moving issue

[SrPx]

Is a bit of 2 issues in a same post, but is all related to lasso selection (maybe other selections, too).  You can mouse-wheel zoom-in /out at light speed with .333 beta, no issues (it's impressive how fast is in that with even big canvases). And consider I am working in a 12700 x 7800 painting canvas (not yet like a 20k or 25k wide photography, but still). But the moment I set a lasso selection, zoom in and out will make appear random big quads of dark color all over the canvas (it's flashes, they disappear). Surely an engine reconstruction/optimization. No big deal,  is just a lil bit distracting, and a non experienced (in graphics apps) user would fear a crash. Is just a glitch.  But prolly sth to fix to not give a wrong sensation. Again, only happens  here with lasso  (edit: happens too with other selections) selections. 

Also, and a bit more of a problem, and reason for this post, once you want to displace these pixels selected by the lasso, it lags a lot, to the point it makes very difficult to position. So, you can drag it and stop the cursor where you think it should stop, but the content and marching ants wont move, just make big jumps in the end, so , where it will end is a wild guess. So, I'd say this would be more important to fix, very clearly (both things are not really as important for painting (although they are for me), as they are for photo retouching and image editing in general. Mostly the moving issue)

BTW, with moving the pixels, I mean pushing and keeping pressed ctrl key while left dragging to move a selection. There also should be some possibility to press a key combo so to besides moving those pixels, you would leave the source intact (similar to a copy and paste, but you avoid creating a new layer, I think has been mentioned before). Works so in PS, is practical. No big deal, tho.

Oki, and after some more fiddling, I realize the random big squares with  fast wheel-zoom if having sth selected, show up less, but still do, in just a 500x500 px canvas.  Yet though, the moving pixel selected by lasso (with ctrl) , that works great (apart from actually being no other option than perform a cut). So, seems the lag and so random placement etc, is fully related to performance in a large canvas with 8 layers in THIS very crappy machine you see in my signature. Surely not showing in anything purchased later than 2009. Or showing up once you push the limits more, ofc.

Cheers,