FS9:Strange stuttering?

HiI have occasionally (rare) problems with stuttering. And usually at same place, approach to LDZA rwy23 at ZAG VOR?Strange thing is that not occurs always.I tested again and this time I put a/c in hold at same VOR for about 1h and nothing happens, it was OK. But when occurs I have pause every 2-3 sec in regular intervals. After touchdown it returns to normal.I check Task manager and it looks like fs9.exe cpu usage was greater then in normal situation , around 40-50%. Question is why in that place. I will expect to have this behavior in some dense areas, but in that part scenery is simple and I would not expect to have stuttering. Mem usage is normal, so I don't think that I have Memory Leak. No any kind of CTD. Just high CPU usage when occurs. Every time this happened, I was online (IVAO) with ASV6 and it happened with DA Fokker 100 (not 100% sure about that, but last few times I fly with Fokker).Any suggestionFs9WinXP 32ATI2900PRO 1GB4GB RAMGE Pro, UT EuropeThanksEdin