Ur CPU doesn't meet the system requirements and by ur gpu (Apu) is an onboard one, witch doens't meet the system requirements, although its still in alpha there might still be a little hope.
Me too, I have a fps of 15 on lowest settings and an fps of 15 on highest settings :/
AMD Phenom II x6 1090T stock 3.4 ghz
AMD HD 6870 1005mhz edition
8 gig ram 1333mhz
psu: 700 watt
Arma 3 alpha system requirements (recommended):
CPU
Recommended: Intel Core i5-2300 or AMD Phenom II X4 940 or better
RAM
Recommended: 4 GB
Video Card
Recommended: NVIDIA GeForce GTX 560 or AMD Radeon HD 7750 with 1 GB VRAM or better
Video Card (for minimum)
Minimum: NVIDIA GeForce 8800GT or AMD Radeon HD 3830 or Intel HD Graphics 4000 with 512 MB VRAM
CPU (for minimum)
Minimum: Intel Dual-Core 2.4 GHz or AMD Dual-Core Athlon 2.5 GHz