SYSECHO raises an event that EG processes, and the interaction could have a small cost. Might be interesting to run your test in a Base SAS environment where EG isn't in the mix. Also, SYSECHO is simply a global statement for SAS to process, so you could try with another such statement (like FOOTNOTE;) and see whether just processing a global statement adds overhead.

For my part, I've always positioned this as a trick to get some feedback via EG and not necessarily a best practice for production jobs. I think it's handy, and I've used it to instrument SAS programs under development. I usually remove the statement when running in Batch, but not sure it has an impact there.