Thaks for answer Stephen.
Its true other formats are very quick loded to vegas10, and work with fullHD video ist smooter like in Vegas7.
But this problem with mjpeg avi its like some bug in Vegas10.
Vegas dont recode the MJpeg file during the load, CPU is 5percent.
I dont know what is Vegas doin durin loading. I use sysinternals process monitor that capture every disk an registry event during load. Vegas7 read one file (avi mjpeg) on 200 events in process monitor Vegas10 1500.
Ithing its bug.
And crash 3 times per hour if i edit mjpeg. AVC crash one per day.