Performance testing environment need to mimic exact production steps. Please find my suggestions and questions

• Yes, You need to use loadbalancer (This is recommended). This would mimic exact production setup
• Do you have exact hardware for performance testing ? Is it a scaled down version ? If it is a scaled down version then
•   How does the loadbalancer work, Is it IP based on request based, If it is IP based then you need to worry much as there would be no routing involved (proxy handling), Depending on it you can decide. Load balancer also has logic to handle load (Round robin, stick etc..)
• Alternatively if you can identify the amount of load single instance can handle you can extrapolate how adding another instance would benefit
• What is the impact of load balancer on application logic, Is it just routing (dumb routing) without adding any impact to functionality

These are some questions to begin with. You can access based on your application and decide on next steps.

Performance testing environment need to mimic exact production steps. Please find my suggestions and questions

• Yes, You need to use loadbalancer (This is recommended). This would mimic exact production setup
• Do you have exact production hardware setup for performance testing ? Is it a scaled down version ? If it is a scaled down version then you need to understand How does the loadbalancer work, Is it IP based or http request based? If it is IP based then you need not worry much as there would be no routing involved (proxy handling), Load balancer also has logic to handle requests(Round robin, sticky sessions etc..)
• Alternatively if you can identify the amount of load, single instance can handle you can extrapolate how adding another instance would benefit
• What is the impact of load balancer on application logic, Is it just routing (dumb routing) ?

These are some questions to begin with. You can assess based on your application implementation and decide on next steps.