It sucks I know, but sometimes things have to be done manually , meaning selling something and buying another to get rid of problems.
Look at me I have an Edirol Fa101 firewire interface that had latency about 5 ms ( using the drivers from edirol). I ran it like that for 2 years before I had enough of it and was about to sell it, due to Me needing lower latencies for guitar work as for midi VSti 5 ms is good enough. But for guitar 5 ms is way to high, something in the 3 ms is better for playing live FX VSt's( amplitube and others). So in the end I decided to take a look at the drivers, reg settings for the interface, and see what settings they had inside the INF install files. This is how I solved the mystery of the FA101 with setting change after change, probably 2 months testing i came up with 3 different reg entries,as it turns out Edirol stores all the card's settings ( the secret ones) right in the registry but it's hard to find it in there. Now with 3 different reg entries i can go to 5 ms, to 2.5 ms and down to 1.5 ms and rock solid stable. All I have to do is power off / on the Fa101 when after the reg entries.
I bought another one by the way, just as a backup. Now this interface is getting to work not just sit around collecting dust.
here is me with my guitar straight into the guitar in on the edirol fa101 then into reaper running Jamvox VST 2.5 edition.