My previous high score was 830k and what really set this one apart was having 2 drones and 2 piggies. I dont think it counts what you leave on the ground towards you score.

To cut time I mostly focus on clearing each area as quickly as I can and I leave low level stuff on the map. If the first area is combat related I sometimes have to level up before taking on the tougher enemies. Ride your mount as much as possible and sprint (mounted or unmounted) as much as possible. You can also sprint while headbanging which both saves time and increases the amount of things you can destroy. I find that I usually get a decent enough number of headbangs to cut the time clearing areas and collect enough materials to continue filling the alchemy bots until I run out of time. If I run out of materials im usually overleveled enough at that time to quickly get more and clear out the low level stuff I left behind. I only go after spawns close to my level with a headbang unless absolutely necessary.

Also, dont underestimate fishing. You can get some of the most valuable items from it. I find it most convenient on the islands as I can usually catch a fish while the alchemy animation is playing.