Well, not sure if this thread is anyway active. Over the past several weeks I have been getting my own issues of a bit of lag here and there on Multiplayer (mainly whenever somebody enters/leaves the server), but the main issues for me was the constant stutter only on multiplayer. It was very prominent while moving on the ground and while in the air making quick movements, i.e aileron roll etc. It was almost unplayable as it was all I was focused on.
Although single-player was buttery smooth no problems there.
My system is overlocked to 4.3ghz. You can see my system specs in my signature. The BCLK speed was running at the stock 100mhz. I have another saved overclock profile which is at around 4.1ghz, and realised that BCLK speed was at 103mhz. Turns out, if I had it at 100mhz on multiplayer the odd stutter would come into play. If i switched it over to 103mhz, it was as smooth as single-player, but of course taking into account that on multiplayer there's a lot going on, and player constantly entering and leaving the server.
Was quite an odd but interesting discovery. Today was the third day I was finally able to fly on multiplayer 1.5.3 without any issues anymore and enjoying DCS again.
Hope this might give others some insight.
Cheers