Hi, I think that this behavior is normal on low-mid end GPUs. I have 750ti and had this drops even in 1.2. I assume that engine needs to render another "pixels" on MFCD and this consumes lot of GPU performance. My friend have GTX 970 and on Full HD and 1024 MFCD res he have drops too, but very small.
Gary:
yeah your NTB have i5 but with M or U letter after numerical description of model like 5200U which means that this CPUs are crippled because of ntb heating, power cunsumption etc. So they are not powerfull as normal desktop models
And same is aplied to your GPU, again M means mobile, so this GPU is much less powerfull than equivalent desktop model and most close is HD6670 which is old "rebranded" and little bit optimalized HD4670 with more RAM so no woonder that your rig "sucks" at DCS