I'm trying to decide whether to get more memory and a hard drive for my Toshiba laptop or to just buy a new laptop. The new HP laptop I'm considering has an AMD Dual-Core A9-9410 APU (2.9 GHz, up to 3.5 GHz, 1 MB cache) + AMD Radeon™ R5 Graphics. My Toshiba laptop has an AMD Quad-Core A6-3420M Accelerated Processor with AMD Radeon™ HD 6520G Graphics o 1.5GHz base(2.4 GHz with AMD Turbo Core Technology), 4MB Cache. What purpose does the 4MB or 1MB Cache serve?