I suppose if the case is that they used to work fine before Accu-feel, then it stands to reason it is demanding more. As I said earlier, you may have to decrease the load of something else to compensate. I've had to set water and cloud textures using REX to very low resolution and set my LOD to 4.5 for example to be able to use add-on airports in dense areas. My worst case scenario was using any complex aircraft within an Orbx region, with REX weather, and an add-on airport, I simply pushed to my 3.4 Gb limit and the simulator failed. It's likely you are now encountering a very similar situation with the addition of Accu-feel. There are no other solutions to the problem. Keep in mind, although FSDT airports run outside the sim in their function, the textures do not and that puts load on the VRAM immediately. It's why they put texture resolution options for CYVR. With Orbx and a somewhat complex aircraft, there was no way I could keep the sim from running out of memory without lowering the texture resolution. I suspect you already know all this, but I'm tossing it out there.
Hopefully Umberto can give you a clearer explanation as he knows how this crap works in more detail.