Is warm up needed ?

I have four services developed with **dot net 6**

- I'm using Fix protocol for communication with client(It is a financial protocol built on TCP )
- I'm using grpc unary communication(internal communication)
- I'm using EF , dapper and ado.net
- I'm using redis
- I'm using the default dependency injection in .net
- Most of services are singleton( there are many singleton services and some of them used for just caching some data )

The problem is the first **20 requests latency** is very high compared with the next requests also if the system is **idle for five minutes** ,the request after this idle time **takes a long time**

How can i identify the problem and what is best solution for this problem ?

Shoud i make a warm up service to send fake requests all the time to keep the system warm but this will affect my real request as i expected a lot of requests at the same time?

If the warm up is the solution what is best practise for applying it ?

thanks