Loss of good performance after en/decryption & ntfs-de/compression

[schober]

hello!

I got my 32gb runcore pro IV some days ago and installed immediately winxp on it.
After installation I did a crystalDiskMark-Bench and achieved very satisfying results:

Seq: read 189.1MB/s write 96.47MB/s
512k: read 150.6MB/s write 91.94MB/s
4k: read 28.84MB/s wrote 8.410MB/s

After that I wanted to test the performance with truecrypt-system-drive encryption and ntfs-filesystem compression.
As the performance was too bad for me with encryption and/or file-compression I retrograde everything with the expectation getting the good results with crystalDiskMark again.
Strangely the performance-results stayed bad after decompressing and de-encrypting.
That worried me and I did a fresh install of winXP, but the performance still has gone and I didn't achieve to recover the speed.

What's going wrong???

Current results are:
Seq: read 117.9MB/s write 33.98MB/s
512k: read 110.3MB/s write 23.52MB/s
4k: read 26.30MB/s wrote 3.379MB/s

besides motherboard makes some noice while reading(only).

thanks for help & regards, schober

ps: my system:
Motherboard: Giga-Byte GA-M51GM-S2G
CPU: AMD Athlon 64 X2 5000+
Chipset: nVidia GeForce 6100 (C51) + MCP51
GPU: nVIDIA GeForce 6100 (C51)
Memory: 2048 MB DDR2-SDRAM
OS: Microsoft Windows XP Professional SP3