This is correct behaviour. It's 2 physical CPU core processor with 4 logical CPU cores what is achieved via Intel® Hyper-Threading Technology. Intel HT can help with multi-threaded operations a little (the gain can be approximately 10%), it depends on inherent characteristics (sequence and type of instructions) of task which is being executed on CPU. Therefore HT can cause even decrease of performance (because physical CPU core cache is divided between two logical CPU cores).