Robin You can submit a feature request to have Evolution compiled with better optimization.
ghostbsd/issuesissues/new?assignees=&labels=feature&template=feature_request.yaml
An example:
CFLAGS+= -O3 -pipe -march=native
CXXFLAGS+= -O3 -pipe -march=native
MAKE_JOBS_NUMBER=12
MAKE_JOBS_NUMBER_LIMIT=12
WITH_CCACHE_BUILD=yes
As an aside, you may want to review the Evolution make config settings to see whether the settings meet your needs. You can do this:
sudo -i
pkg install ports
cd /usr/ports/mail/evolution
make config
Here is what you will find.

If there is another option that you need enabled, submit a feature request.
ghostbsd/issuesissues/new?assignees=&labels=feature&template=feature_request.yaml
If you do not want to submit feature requests, you can manually managed the Evolution build yourself by using GhostBSD ports. You would need to rebuild Evolution each time there is a change to Evolution sources.
sudo -i
pkg install \-g 'GhostBSD\*-dev'
pkg install ports
cd /usr/ports/mail/evolution
make config
env CFLAGS="-O3 -pipe -march=native" CXXFLAGS="-O3 -pipe -march=native" make install clean