Well, actually the problem was in the file dlls/winex11.drv/bitblt.c in the function Code: /*********************************************************************** * X11DRV_StretchBlt */ BOOL CDECL X11DRV_StretchBlt( X11DRV_PDEVICE *physDevDst, INT xDst, INT yDst, INT widthDst, INT heightDst, X11DRV_PDEVICE *physDevSrc, INT xSrc, INT ySrc, INT widthSrc, INT heightSrc, DWORD rop ) because after issuing the command > WINEDEBUG=+bitblt wine ./App.exe there were a lot of trace:bitblt:X11DRV_StretchBlt rectdst=25,1 1x13 orgdst=10,10 visdst=(25,1)-(26,14) trace:bitblt:X11DRV_StretchBlt rectsrc=0,0 1x13 orgsrc=0,0 vissrc=(0,0)-(1,13) trace:bitblt:BitBlt hdcSrc=0x3ed0 0,0 -> hdcDest=0x1ec8 25,1 1x13 rop=660046 trace:bitblt:X11DRV_StretchBlt rectdst=25,1 1x13 orgdst=10,10 visdst=(25,1)-(26,14) trace:bitblt:X11DRV_StretchBlt rectsrc=0,0 1x13 orgsrc=0,0 vissrc=(0,0)-(1,13) that were synchronized with the slow display of the buttons and text input fields. Can anyone provivde me an optimized version of this function? Thanks very much Amox