Hangs waiting for URL / cache in Chrome with Squid3

I have installed squid3 and defined it as explicit (non transparent) proxy. In most cases on most sites it work fine, but on others it appear constant problems with hanging page downloading.

On hang some URL is reported "waiting" in Chrome status bar:

URL is random, sometimes it is

Waiting for cache

Also waiting animation constantly runs at page tab:

Waiting never ends.

Looks like I encounter some limit of coections or something.