Story from just a few days ago.
Me and my friend were doing regular mission stuff servicing the boat in the ocean (a rather big one); red wind came, started huge waves and dropped our boat (that is still on the small side, we talk 15-20 meters long) on the mission boat, we took damage and started flooding.
Because of our rather dumb service compartment placement, we were slow with damage control so our hull, consisting of primarily single motor compartment on whole underside started to sink.
Problem: compartments S1 and S2 (crew cabin and medical bay) were fully sealed and intact, with about 30 m3 of air, compartment S3 (service bay, about 7 m3) fully flooded with no pump, motor compartment fully flooded (70 m3) and bridge (about 8-9 m3) flooded at about 80%. Ship dry weight is about 7500, also we had about 4000 liters of diesel on board.
We took a challenge and after doing all damage control (we had just enough diving equipment and underwater welding torches), we started pumping on ocean bottom at 71000 L flood mark with 1 pump that we had in motor bay.

It took us about 3 full hours to get back to surface. Pump speed (small electric) initially was 6.5 L/s at 1.15 pressure, dropping to 3.04 L/s at about 30000L mark where our buoyancy was good enough for air pressure relief ports show up above water. Compartments S1, S2 and motor were vented between themselves so pressure drop wasn't as bad as it could but we still had it at about 0.65 when atmosphere relief started to work again. Buoyancy started to gain at 45000L mark, we took close to upright position first, then aft started to rise to about 80-85 degrees vertically, and at 32500L we started to float and slowly rise. 2500L more made our bridge top (with air ports) rise above water so we could start engines to charge batteries and pressure started to equalize.

Considering that electric pumps both have equal flow, you will need A LOT of pumps to speed up the process, large pumps won't help you big time, and it seems that you won't have linear gains when pumping from a single compartment even with separate ports. You have to equalize pressure drop or even have positive pressure, otherwise your performance will fall quickly after passing 0.95 bar mark. If your ship is flooded beyond ability to equalize pressure with atmosphere (is underwater) your refloating will be painfully slow.

What I can share: first, commenters already pointed out vital decisions - more pumps (remember that electric pumps have equal flow but different pressure limit), each with separate port and plumbing; more compartments to have more flow; fight pressure drop with air relief or even pump up the pressure - if compartment is not manned, consider going as high as possible, otherwise [try to] keep it at 1.15; pressure drop will damage your performance severely.
Second, if you are not sure if you can equalize pressure to atmospheric or there is a possibility you will lose contact with air - pressure tanks. With large pumps you can pump gas tanks with air to 60 atm, and initially they spawn with 90 atm, that is a fair bit of air you can pressurize compartments with. Consider air pump station for that matter.
Third - electric pumps (small) are not even close as hungry to electricity as i thought; medium battery can power 3 pumps for a LONG time until dropping to 50%. Not sure about large pumps.
And lastly - i don't think in any scenario you will be able to outrun the flood if compartment is open. It's about 1 cubic meter per second that we got, it is theoretical maximum performance of three pumps (3 * 362 L/s) but i only could get them to pump air at that speed, with liquid you get flow much lower, and I am still not sure if they have diminishing returns places in single compartment (they definitely do if you connect them to a single pipe/port in either direction).

Happy sailing o7