Fish -assuming that the 5km and the 10k courses are similar ...
If your 10k time is 1:10:10, that's a pace of 7:01
If your 5k time is 33:55, that's a pace of 6:47
It might not sound much, but 14 seconds per Km is a lot faster.
There is 17 secs between my 5km and 10km paces ,and another 17 sec between 10km and HM pace ( roughly ) . Although I'm working on it 
Maybe you are better suited to endurance rather than speed . It's something complicated to do with slow twitch and fast twitch fibres in muscles I think.