I have a strange problem with slow load of relatively large files. On a domain without proxy (designed for serving static files), the request time (as monitored by access log $request_time) for an simple jpg image file of 5KB is 0.000s (seems to be shorter than 1ms). Thus, one expect to load an image file of 15KB within 3ms, but surprisingly it takes about 600ms. A static file of 15KB is not big at all; but there should be a threshold which leads to this slow down upon slightly increasing the file size.