Exactly where are you seeing high CPU usage? If you've gone to Settings > About Phone > Battery use and seen Android System at around 95% then this is not CPU usage. Showing "Android system" as 95% means that the Android System is currently using 95% of the current power usage. It doesn't mean that it's using 95% of the battery (it could be using 20% really) but if nothing else is utilising battery then this figure will be higher.
I completely understand what you're saying. But on most Android phones, you typically get roughly 30% cell standby, 30% phone idle, and 5% Android System. Whereas FLB R7a (and R6a) typically show 98% Android System.
This can mean one of 3 things:
1) Android System is using far more resources than expected in FLB ROMs
2) Other processes are exceptionally efficient on FLB ROMs
3) The FLB kernel is reporting certain processes as being part of Android System, whereas other Android systems show them as separate processes.
As a comparison, I flashed Seb's de-crossed ROM, and the battery use statistics are back to what I'd normally expect. So there's definitely something strange going on....