if u quit ur job, it will not affect ur federal processing cos point calculation for job is usually done under the selection stage which ur BIQ has done. the federal only deals with admission and not selection issues hence only medical and criminality check comes in here..
having said that, i will advice that, yeah, if u need take a short brake for to refresh, pls do so that u wont end up coming up with a medical complication that might affect ur medicals.... but quitting the job totally to me is too extreme cos this is the time u need to begin saving money cos medicals will cost u money, getting ur ticket to go collect ur visa or the cost of courier will cost u money, u will need get a ticket to montreal, u need ur proof of fund... unless of course u already have enough u may wish to sit with ur hands Akimbo.....u need money bro and u also need rest.. try to stike a balance..... u do no even know aw long the federal part will take to finalize...trust me if u quit ur job, u will only throw urself into anxiety mood cos it is evry seconds u will keep checking e-cas for an update on ur file and that in it self is a stress inducer