[Private200]

I think your pc is slow , and it have nothing to do with the video card , just upgrade your pc ram memory,

1st It is not sa-mp bug . Try to open it in single player , and if it happends there too , then you should upgrade computer speed ,
2st It is not reported by anyone else , so if this doesent happend in single player , then the problem is your pc or gta san andreas

PS : Whats the ram of your pc ? Reply me

Thanks
Private