The T8100 and T9500 processors are identical
except for their bus/core ratio (multiplier) and resulting max. clock speeds. They differ in the size of the cache, but since both chips use the same die, they actually have the same amount of cache, with the reported difference being disabled in the T8100. They both have a max. TDP of 35W, however the actual consumption of each will likely vary proportionately to their clock speed differences, but even then that difference would only be noticed when the CPU was running at max. speed, which is actually very little of the time in a modern system where the CPU is dynamically throttled to match the load. In other words, the T9500 is about 20% faster than the T8100, so it would likely use that much more power, but only when both were running at max. speed, which is probably 10% or less of the time during normal use.
Combine that with the fact that the processor consumes about 10% or less of the overall total system energy
, and you have a case where the difference in overall power consumption using one chip vs. the other (assuming that both are running at max. speed 100% of the time) would be around 20% of 10% or about 2% overall. If you add in the fact that the CPU would only run at max. speed about 10% of the time during normal operation, then that difference would drop to 0.2%.
So, in summary I'd estimate that changing from the T8100 to the T9500 would result in about a 2% to 0.2% loss in battery life overall. Scott.