this sounds a bit contrary to what I heard before that battles are rather slow. I mean, I like battles rather drawn out, long, with time to react. its not a problem if flak frigates totaly own strike craft - that's what they are supposed to do - but a) maybe not that extreme and

not so fast. I mean ... such big fleets destroyed in under a minute? where is the epic in that? where is the "lust stop and watch the battle for a few seconds" effect? just my 2 cents.
There is an easy solution for that. Change the PlayerTech.entity in the GameInfo folder:
shieldData
shieldAbsorbGrowthPerDamage 0.001
shieldAbsorbDecayRate 0.0125
shieldAbsorbBaseMin 0.2
shieldAbsorbBaseMax 0.6
Change the first to about 0.0015, third to 0.4 and the last to 0.8.
Battles will now last quite a bit longer.
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My examples were a bit harsh anyway. It's only late game fleets of more then 10 high lvl capital ships with 40+ frigates that shredder enemy attack fleets of 15 frigates plus 20 cruisers in this amount of time. And its only because the AI doesn't do a very good job of attack fleet compositions at the moment. Hoshiko Robotic Cruisers just don't have much of a shield and hp to survive for very long.
Battles with equal fleets can last quite some time. I had once a battle over an insignificant dead asteroid which lasted for more then 15 minutes, since the AI and I were jumping in reinforcements in at about the same rate and we both weren't able to make significant losses to the other one.
Imo if the AI gets better in fleet composition, battles will get to last longer (and be quite harder).