It shouldn't, that's the whole reason SMT exists. If there is detectable jitter that would be notable.
People have a bad taste in their mouth that was left circa ~2000(?) from some Intel parts with a pipeline that was too deep. Ever since that was fixed most workloads do see a 2x speedup when enabling SMT.
SMT sibling threads can definitely impact each other. It works great for common workloads. If you have a highly tuned workload with high IPC or want to trade off throughput for latency, disabling SMT can be a win. Disabling SMT also increases effective L1 and L2 cache which can be beneficial.
People have a bad taste in their mouth that was left circa ~2000(?) from some Intel parts with a pipeline that was too deep. Ever since that was fixed most workloads do see a 2x speedup when enabling SMT.