Frames missing when recording

On an iMac we using BoinxTV for layers and CamTwit and FMLE for live broadcast.
During recording we can see we have frames missing.
There are no droped frames and the graphic card usage is only between 25 and 30%, so now and then even less.
We do see like we only use 10 or 15 frames instead of 25.
We are using apple intermediate codec
Do you have any idea how to solve this?

What frame rate you setup the BoinxTV document on? Are you recording with BoinxTV?