in conky other than % of cpu load there is also a load 1/5/15, what load is the later one?

after 11 days of uptime my n900 is becoming less responsive, especially if multitasking and one of the program running is the web browser. when becoming really slow & i look in conky the cpu is only less than 30% in 600 mhz, but the load 1 is very high up to 8.5
the only solution for this so far is to restart my n900 and after that the load 1 rarely exceed 1.5 even multitasking several programs

was wondering, is there something wrong with my n900?
only noticed this after update to PR 1.3 by flashing