TB2 is akin to using one of those x16 slots that's wired to x4 (or worse, since if you're using a Gen3 x16 GPU, you'd be running at Gen2 x4, which would be an e

TB2 is akin to using one of those x16 slots that's wired to x4 (or worse, since if you're using a Gen3 x16 GPU, you'd be running at Gen2 x4, which would be an eightfold reduction). It'll depend on your workload, but generally, it is going to be visibly slower than the "baseline" performance for any high-utilization workload.