Files slow to load with codec pack?

If I use the K-Lite codec pack or my current MegaCodec pack it takes several seconds to load the video in any player other then VideoLAN. I am using the full install and I install most of the codecs as otherwise I do occasionally run into a unplayable file.

When I install the codec pack and use individual codec installers everything works fast but does not support everything I need.

Anybody know which codecs or settings can cause this slowdown.

Thanks

If I install ffdshow and no video filters then it works fast but the problem is that ffdshow always becomes unstable and unusable after some time so I don't like using it to much.