From Longman Dictionary of Contemporary Englishhot up phrasal verb British English informal1 INCREASE IN ACTIVITY, FEELINGS ETCif something hots up, there is more activity or excitement Things generally hot up a few days before the race.2 the pace hots up used to say that the speed of something increases → hot→ See Verb table
Examples from the Corpus
the pace hots up• Remember this when the pace hots up! 