You see I am no plumber!
My gas boiler started to play up, and I was sure it was circulating pump, so I changed it - it was difficult and rusty, water everywhere!
It cured it, so I thought - then it played up again, so I changed something else - no it wasn't that either! Dammmn.
Finally I called a plumber, guy came in, half his arse showing through his belt, he put his hand in there, loosened a thumb-screw (I was watching like a hawk), it hissed and some air came out and when it started dripping, he closed the screw - 150 quid please! . . . . I paid with my jaw still on the floor! it was fixed.
Can you get my drift?
Those who are not knowledgable about something, assume thick'n'thin, blame this'n'that and keep missing the point that insists Keep to what you know!
No, it is not the cache, nor the speed of the connection or the speed of your CPU.
Just because you don't know what's causing the issues you are having, it doesn't mean it is a mystery and/or larger cache would cure it!
Standard un-compressed CD music (not flac, not MP3 ...) has a data rate of 1.4Mb/s (8 bits to a byte) means 0.175MBytes per second. This is the original data-rate off the disc without any attempt to make it smaller (flac is about half to 1/3, MP3 is tiny).
An old fashion rotating hard disk (not SSD) of 20 years ago(!) had a sustained read speed of about 50 Mbytes per second - you see why it has nothing to do with that?