I think folks are misunderstanding shield mechanics. Regeneration is not the problem with shields in most cases, since shield regeneration tech is the amount of shield points regenerated per HS per five minutes. Even a size-50 generator at MaxTech (regen 15) can only regenerate 12.5 points of shield per 5-sec increment, and with the kind of weapons you should be using at MaxTech this should not be a difficult amount to punch through. Shields are stronger against high-damage weapons because they negate the armor penetration profile of such weapons, the regeneration rate is a relatively minor consideration.
The only exception to this is if you are using missiles, only firing a wave every few minutes or longer, and not using enough to overwhelm the enemy PD + shields + armor to actually destroy the ship, which usually means you have either made a serious tactical error or have not done sufficient reconnaissance.
The problem with shields, if you consider it a problem, is that they are too efficient relative to armor in terms of raw damage absorption. This is due in large part to the scaling of Size^(3/2) which leads to size-50 shield generators providing about 75% of the same damage absorption as armor at the equivalent tech level. With armor, a generally accepted rule of thumb is that a ship will consistently take internal damage once its armor integrity drops below 50%, whereas for shields the entire shield must be defeated to deal any other damage, so in practice shields have a clear tactical superiority over armor in addition to their intended strategic superiority (due to not requiring expensive repair work). If we need to fix shields, I would prefer to see this scaling rebalanced so that armor remains a viable tactical option, rather than worrying about regeneration.
That being said, the suggested change would be an interesting way to add some balance here. At MaxTech, where shields are most powerful relative to armor, the strongest possible shield is 50*sqrt(50/10)*15 = 1677 strength, so a weapon with more than sqrt(1677) = 41 damage will leak through. The MaxTech particle lance can reach 100 damage, IIRC, so still 59 damage will leak through and likely drill a hole into the ship's interior. Similarly, a MaxTech advanced spinal laser (120cm) would deal something in the range of 400 damage (I don't have the game at hand to check this), most of that would get through a shield as well. If anything maybe the sqrt scaling is too much, but I think it is at least interesting to consider as another tactical option - the disadvantage of such high-damage weapons is their very slow ROF, so a fleet with higher-DPS weapons will be able to strike back several times even if the initial exchange of fire is unfavorable.