If you're working with something old enough for encrypted connections to be "CPU intensive", you're probably not talking to anything remotely current any way
TLS 1.3 is out there
TLS 1.2 is ubiquitious
I cannot recall the last time I saw anything older than TLS 1.1 anywhere - TLS 1.1 on down into the various SSL specs are all deprecated/unsupported[0]
TLS 1.1 and 1.0 have been deprecated for 2 years, SSL3 since 2015, SSL2 since 2011
If you're running something new enough to support TLS 1.1 (at least, 1.2 or 1.3 are much better), then the encryption overhead is very tiny
TLS 1.3 is out there
TLS 1.2 is ubiquitious
I cannot recall the last time I saw anything older than TLS 1.1 anywhere - TLS 1.1 on down into the various SSL specs are all deprecated/unsupported[0]
TLS 1.1 and 1.0 have been deprecated for 2 years, SSL3 since 2015, SSL2 since 2011
If you're running something new enough to support TLS 1.1 (at least, 1.2 or 1.3 are much better), then the encryption overhead is very tiny
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[0] https://en.wikipedia.org/wiki/Transport_Layer_Security