Even if you could get the "is this cell of the table calculated?" check down to one cycle (which you can't, 6502 branch instructions take 2-4 cycles, plus a few more operations to check the table calculation status), it's still gonna add one cycle to a hot loop that's done 43k times. Pre-calcing the entire table only burns 6k cycles, and can probably be done while displaying some transitional effect that requires very little CPU.
If we presume this scaling operation will be done more than one time (which it probably will be if it's getting this level of optimization) then it gets even worse.
Good analysis. I guess I lost my cycle-counting foo, because on modern CPUs cycle-counting is a) infeasible on a superscalar, speculative, out-of-order CPU, and b) even if you did manage to do it, it hardly matters when a CPU cycle is less than a nanosecond, but any memory access that slips through the caches means many orders of magnitude higher latency.
Of course none of that applies here, but it colors the way you think about things…
meanwhile the 6502 is all "cache? what's cache", every 6502 optimization is basically a pessimization for modern CPUs.