Unfortunately, there is no clear “yes” or “no” answer.
The answer depends on a lot of factors and the number of clients is one of less signficant ones of these factors. And as I’ve tried to explain when responding to your previous topics on the same theme, in your particular case, the firewall configuration is far from optimal for throughput.
Sadly, only after spending the effort to optimize the configuration you can find out whether it was worth it or not. No doubt that optimisation will speed up your router, but the question is whether it will speed it up enough, i.e. to a point where the router will not be the bottleneck any more.