Client-side software testing helps in checking the performance of operations done with the help of devices like - placing a request to the server while waiting for the revert from the server in the form of data that will continue to turn into a webpage that will be shown on the users’ browser.
Server-side testing means that the experimentation (the change to content) happens on the company’s web server. The server determines the version a visitor sees during the page load process, as opposed to after.
You should consider having a good mix.
Caveat your analysis in client-side tests.
You should consider doing more same-session experimentation/optimization w/ client-side tests.