Finally chopped in the old modem & television box - they'd been playing up for months - & so I'm upstairs trying out the new connection. I'd hoped that this would have solved the recurrent problem of a sluggish connection to the internet. Hopes dashed. For some reason, on starting a new session, the Mac starts searching once again for a Wi-Fi connection - which it patently has (little antenna sign in full, Network statistics all looking fine). The issue seems to be with an Ethernet connection which - obviously - I don't need. This goes into a spin as it searches for the (non-existent) link. Why Ethernet when I'm using Wi-fi? I go into Network Preferences, switch Ethernet off, only to find it reconnecting itself moments later. Duh? What sadistic geek at Apple has programmed this irritating little glitch into the Yosemite OS?

I'm loathe to start fiddling with deeper layers of the set-up but the 3 to 4 minute wait as whatever it is sorts itself out is fairly tedious. (So much for the State of the Art Operating System - it feels like I'm back twenty years with a dial-up modem *squeak-screeeech* tones). Then, suddenly, everything has settled down & the pages load in a jiffy. Magic!

If anyone has experienced a similar problem & found the solution - please let me know.