For many years with Workstation 4.x/5.x/6.x, I ran 1-2 VMs, in a single core 32-bit Pentium M, 32-bit XP Professional host. The VMs were generally development/test environments meanwhile the host PC was for stuff like Office. Were there days I wished I had something more powerful or more memory than the 3.5GiiB that the XP could use with Intel PAE? Sure. But, sometimes you just have to work with what you have.
Note that i3-6100 also has hyperthreading so it will have 4 threads.
http://ark.intel.com/products/90729/Intel-Core-i3-6100-Processor-3M-Cache-3_70-GHz
I suggest you try it out first as only you know what you want to do with the 3 VMs; and only you can judge/decide whether the performance is acceptable to your purpose.
