Raise FSG_NUM_BUFFERS to 4. Benchmark showed a little increment over previous value, 3.
Revert higmem_is_dirtyable to 0. Still inconclusive, but it seems to cause trouble at least with zram enabled (note published kernels has zram but it's inactive by lack of enable support in the rom config. I'm using a script to test internally and will only be able to recommend for/against zram after testing a lot more.
removed HPORCH32 setting from defconfig so that the user is forced to make a choice