Your song's BPM setting (1/Cd on the Song's GLob page) flows through to the tempo of many things, from LFO speed divisors to the delay effects; a change in BPM will never throw off any tempo-based aspects of your song.
Everything syncs up throughout the synthesis engine, pattern playback and song mode. This makes your songs sound like well-planned, evolving pieces of music. Sync-locked LFOs can help with subtle build-ups, textures and "ear candy".
Settings that govern tempo (such as LFO rates) or length, often have their settings expressed in terms of sixteenth note steps ("St" or "S") or, alternatively, bars ("b"). A bar is 16 steps.