How are you measuring throughput? From the Tools tab on the switch or from a wired client using some other test method? If you're talking about the Tools tab throughput test that won't show maximum speed of the switch or internet circuit. Not even close.
And, MS390s will generally show a much faster throughput using the dashboard test tool versus traditional models like MS35x, 2xx, 1xx due to underlying architectural & software differences.
To measure wired client throughput you should be using standard tools like iPerf, speedtest.net, etc.
Are you troubleshooting a specific issue here or just seeing unexpected results using the throughput test?
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