You could look at cpu cache statistics with and without it enabled. Memory access can definitely be a bottleneck. But I guess it wouldn't make too much sense in

You could look at cpu cache statistics with and without it enabled. Memory access can definitely be a bottleneck. But I guess it wouldn't make too much sense in this example (maybe?). But if it is stalled on memory access, maybe disabling hyper threading gives you more cpu registers and/or cache space. Think Brendan Gregg's blog has some pertinent info about this topic.