Road To Black Sea lagging, low FPS

[Ivanko1]

Good night. Recently I purchase Road To Black Sea (I have all map dlc's now) and start to get achivements, starting from Orient Express, to get to Istambul and make Turkish Delight.
But then I cross borders of this dlc - game start lagging. I have similar lag's on other maps, but they are very rare and shown as drop fps rate from usual 20-30 fps to 3-6 fps when entering city.
And then closer I get to Turkey - then more lags it have. After Turk border truck start "teleporting" - like it 1-2 fps, but Steam counter still shows 23-24-1-23-24 fps.
In Istanbul it self is totall mess: 1-2 sec works as usual, then shows 1 frame per 2-5 seconds (0.2-0.5 fps).
And one more thing - then it happens, HDD led flashing like crazy. I made defragmentation for all chapters (Steam is on second separate chapter) - not help.
After that, I make fast travel to Glasgo and made External contract to Narva - works fine, as usual 20-30 fps.
graphic settings usually High with reduced Scaling to <100% (using 50-100). Trying to set Minimal - same thing, just a bit better.
Game 1.36.2.55s. Mods: Sisl cabin accesories and TruckAtHome paintjob, both from workshop.
PC: Phenom II 945 C3 (Thermalright Sl-128), AM2+ MB, DDR2 6Gb, Radeon 6750 1Gb, HDD Samsung 642JJ, Windows 7 PRO 64-bit. Playing on keyboard.

[JURGEN254]

Quote removed - Don't quote the post above - Rule 2.12

Did you manage to solve this?

[CarbonGTGaming]

Try removing SISLs cabin accessories mod that can cause a bit FPS drop cos I had that too and also speaking of Istanbul the city is quite detailed in which is causing your FPS to drop dramatically try turning some settings down

[JURGEN254]

Quote removed - Don't quote the post above - Rule 2.12

Really don't have any issues with cab accessories since I don't use them that much, issue is the stuttering which I don't experience even on Promods

[plykkegaard]

Isnt the Radeon 6750 a bit below minimum?

[CarbonGTGaming]

Promods map and Sisls cabin mods can push your CPU to the limit along with GPU but plykkegaard got a point about your specs it’s not at minimum requirements to play the game smoothly it’s best that you upgrade though