Slowness/Semi-Frozen Notes state after some period of inactivity

Hi guys,I am using Notes 6.0.1 CF1 to access Domino server through port 1352 from Internet using publicaly visible DMZ address of the Domino server. Firewall has 1352 opened for TCP. Works wonderful from home office (cable connection). However, what make my life misarable - if I left Notes without any activity for about 20…30 min, Notes goes to some kind of semi-frozen, slow mode (no response). It wakes up after that for 2…4 min (no crash, just no response) and then it works again just wonderful with very reasonable response time. Auto-refresh is enabled. By the way what is the default refresh time interval? Is it possible to change it? Please help, the slowness poisons my life… Thanks in advance.