From Chromium source code:
--disk-cache-size command line parameter
// Forces the maximum disk space to be used by the disk cache, in bytes.`
const char kDiskCacheSize = "disk-cache-size";`
chrome.exe --disk-cache-size=16000000 would give you approximately 16 MiB of disk cache (not very useful imho).
You must have pretty fast internet if you think it's slower to cache than to fetch off the network, though. I have used insanely slow laptop HDDs and caching to disk is still 10 times faster than fetching off the network. Even if you have a dedicated 100 Mbps pipe, you still have to deal with the latency of servers you're hitting -- something which is completely out of your control -- and many useful websites have performance problems (e.g. StackExchange sites occasionally do...)
With that said, having lots of RAM is a huge boost. If you have enough RAM that the operating system will load a large chunk, or all, of your disk cache into memory while Chrome is running, then surfing static web pages that you often visit is going to be as fast as clicking through an offline
.chm HTML help file :P So if you're looking for a place where you can upgrade your hardware to improve performance, having more RAM (not faster RAM, not a faster HDD, etc) is the prime mover for performance. Plain and simple. Keeping lots of available RAM, low application memory pressure, and lots of disk pages cached in RAM is the primary way to have a "whoa, that's uber fast" experience. Personally I have 16 GB of RAM in my laptop and 32 GB in my desktop, and I'm salivating over ideas of the Ivy Bridge EP chipset upcoming which should allow up to 64 GB if I read the spec predictions correctly.