I tested Chrome and Firefox about 1 week ago. On about 30 tabs, Firefox uses about 1G more RAM than Chrome. Their speed is difference is unnoticeable. I also tested Edge and Vivaldi for RAM usage. The result is Chrome < Edge < Firefox < Vivaldi.
Those results say nothing. Were you RAM-constrained? When I am not, I have found that Firefox tries to use more memory. If I use Firefox while also having 3 VMs running and compiling stuff it stays down, whereas if I don't it easily starts using over 4gb (i have 64).
