High disk usage on 8.5.2 FP1

since upgrading to 8.5.2FP1/64 on windows 2003/64 most of our servers are really slow and we get disk errors.in windows performance monitor we have a very high disk queue length.

we have a additional server with the same hardware and the same user count on 8.5.1 FP5 without any problems.

any suggestions?