Yes, the CPU is the bottleneck at the moment, but your graphics card don’t have enough memory, well, for working yes, but not enough for smooth performance.
I suggest you play on small maps at the moment. You need at least 3 GB VRAM for your graphics card for optimal performance. Try reducing texture levels in the options for better gameplay. Currently the ordinary RAM have to manage the data and transfer it between your graphics card and memory, which can cause major staggering.
I do hope the dev can put more attention in the coding of the game to optimise the performance.