Even the fastest computers can't coop well with huge maps and a lot of civs. Extreme map settings (362x362 tiles) with extreme numbers of civs (31) result in extremely long interturns (> 2 hours!). Calculating trade routes is a very important aspect, so when you build/destroy a harbor or airport, (dis)connect resources and luxuries, declare war or make peace - to name a few events- trade routes have to recalculated. If you want to avoid long waits, play standard maps with 8 civs.