As said, electric reels either home made or shop bought are excellent time savers and they save your energy as well.
At least a 35cm brush with a wide and heavy flow of water, be it fan jets, several jets or bissel type cannon bars etc.
Optional, but I like many agree that hot water helps as well!
Then its a case of working smarter perhaps. For instance some over scrub and over rinse the windows, because in their minds a window isnt clean unless its cleaned x number of times. Spend some time and notice how many strokes of the brush will get a window cleaned, ie snail/slug trails n spider poop etc. With my brush, i know that two passes and a third for the rinse is all that is needed, unless I notice anything different on the window.
This way, your not over working and you have peace of mind, knowing you are doing a quality job but a quick job.
If you can go around the whole house cleaning the tops first and clean downstairs on the way back also saves time where you can. Your not messing about extending the pole every couple of minutes etc.....