There are benchmarks readily available if you search “nginx unit php benchmark” (some that show an order of magnitude reduction in latency) without the quotes,

There are benchmarks readily available if you search “nginx unit php benchmark” (some that show an order of magnitude reduction in latency) without the quotes, but I hesitate to link to any of them as configuring nginx is highly complicated and has so many knobs, particularly with backend upstreams that can be configured in a myriad of ways. My advice would be to try and see.