There is no specific limit to the number of rules you can run on any of our appliances.
That said, if you have ~2k rules, managing the rulebase can become problematic.
It's likely you may have some duplicate or redundant rules or can combine some rules.
Also, types and order of rules will have more of a CPU impact than the number of rules.
General performance troubleshooting steps are probably in order.
You can start here: Best Practices - Security Gateway Performance
You may also benefit from a SmartOptimize exercise with Check Point Professional Services.