EZ Drummer 64 long loops hanging up Sonar

I use EZ Drummer 64 in Sonar 8.5.  After I drop a clip in and enable looping, if I stretch the loop too far, like 40 bars or so.  Sonar will start glitching like it was out of memory. It shouldn't, I have 8 gigs and the project is pretty simple.  If I start throwing a bunch of loops in to a track really fast the program will hang too.   When I make the loop chains smaller, like 10 reps, the problem goes away.  Anyone else seen this problem?