Well any time you start yanking levers and spinning dials you'd better know where the breaking points in your system are.
If you care about the traffic because you're already having trouble with that many simultaneous requests, then you are definitely not going to solve that problem by increasing the response time by a factor of 10.
But an important property of reverse proxies is that once the proxy sees the last byte of the response, the originating server is no longer involved in the transaction. The proxy server is stuck ferrying bits over a slow connection, and hopefully is designed for that sort of work load. If the payload is a static file, as it is in both of these cases, then it should be cheap for the server to retrieve them.
If you care about the traffic because you're already having trouble with that many simultaneous requests, then you are definitely not going to solve that problem by increasing the response time by a factor of 10.
But an important property of reverse proxies is that once the proxy sees the last byte of the response, the originating server is no longer involved in the transaction. The proxy server is stuck ferrying bits over a slow connection, and hopefully is designed for that sort of work load. If the payload is a static file, as it is in both of these cases, then it should be cheap for the server to retrieve them.