This manuver is deliberate and DWEEBISH and has nothing to do with connect/lag. I get consistently high frame rates and can easily distinguish between lag and the "floppy fish", and what AvidMC is describing is NOT lag. These guys are "gaming the game" .. no ifs, ands, or buts about it.
The biggest perpetrator's of the "floppy fish/stick Stirrin" manuver I have found are 109s, 190s and occasionally P47s. Once you get on their six and send a few rounds into them, the floppin starts and if you are not in a LA-7 or another fast plane, this "floppin" can continue, without serious degradation in E, until they extend.
This type of flying I would think is beyond what the human body could endure and I could almost bet the ranch that it was never used in RL nor is it taught in any air combat schooling. In RL you might be able to get away with a few wild jinks, but to continue sustained jinking like that ... I don't think so.
I would like to see (somehow) HiTech put some sort of redout/backout type consequence when the flight controls are used wildly to create such manuvers.