i5's from the same generation (first number if 4 digits) are generally faster. General rule for Skylake (7xxx): i3s are 2 cores with Hyperthreading, i5s are 2 and 4 cores without Hyperthreading, and i7s are 4+ cores with Hyperthreading. Hyperthreading means each physical core is represented as 2 logical cores. This is an advantage with content production or other core-heavy conputation such as virtualisation. Games however mostly need CPU speed. Normally i recommend an i3 for web browsing and some light gaming, an i5 for more intensive games, and an i7 for streaming, content production, etc.