One approach to mitigate this issue would be to create multiple APIM gateways and distribute the Logic Apps across them. This would help to reduce the number of Logic Apps that need to be added to a single APIM gateway and therefore reduce the load on that gateway.
Another approach would be to use Azure Front Door service to handle the routing of the requests to the appropriate Logic App. Azure Front Door service provides a global HTTP(s) load balancer that allows you to distribute traffic across multiple backends based on rules that you define. This can help to distribute the load and improve the performance of your API management solution.
Additionally, you can also use caching and rate limiting features in APIM to improve the performance. You may also want to consider using a Content Delivery Network (CDN) to cache static content and reduce the load on the APIM gateway and Logic App.
Ultimately, the best approach will depend on the specific requirements of your API management solution and the resources available to you. It may be a good idea to test different approaches and monitor the performance of your solution to determine the best approach for your use case.