Is it good practice to enable IPS on the core SRX to inspect internal traffic?
Please mention bad impacts to normal traffic.
On the edge SRX IPS is enabled.
Defense in depth is always a good idea. The limitations are the capacity of the specific model to handle the size of the traffic inspected if it is an existing system.
On the data sheet for you model you can see the size of IDP inspection that can be generally done. You then compare this to the amount of traffic on the policies you want to enable inspection to see if the device can handle the load or not. Be sure to understand both peak traffic and your general growth curve.