Nothing's hogging the CPU.
traceroute is seriously fecked! It times out forever whether I ping the IP address or the name (which resolves instantly).
I think I must have made some Bad Decision during the install. Part of me wants to throw it away and start again, but a bigger part wants to fix it.
Dave (of bdisystems.co.uk) reckons it sounds like there's a DNS thingy timing out somewhere and then it's falling back to a second one that works, and that's why it takes ages to get each file but they get got eventually.
I'll get there!