said by knarf829:They have been using both cores for a while now. said by Thinkdiff:
The XL4 can be significantly slower than the TiVo HD due to the new HDUI (based on Flash, not Java) and just the hardware being a bit underpowered.
I've read that it's currently only using one core of a dual core processor because they had reliability issues when activating the second core. Don't know if this is still the case or if it was resolved in a subsequent update. I've never seen a serious lag (but I also don't use the YouTube app).