DB load balancer

We have a multi tenant model DB with a Primary and a Secondary. There are 3x or 4x connections flowing to Secondary as the application is read intensive. Accordingly we have allocated more number of resources to the VM hosting the secondary/replica DB. 

Spec:- 

Primary: 48 CPUs, 48GB memory

Secondary: 80 CPUs, 128GB memory

PG version: 12.22 (we have already started the upgrade process)

OS: Ubuntu

The problem very frequently we are experiencing is that the CPU load on the SECONDARY is going very very high causing the app slowness. Also, frequently the postgres is crashing due to OOM.

I was thinking of these (please give feedback):

1. Have a DB level balancer for the load balancing in the DB level, meaning primary will also receive the READ traffic

2. Add a second REPLICA and configure load balancer for the connection load balancing

What do we do for load balancing at the DB level, in postgres?

If there are any suggestions, please let me know.

Regards

Siraj