I have a combination of Speeddial 1.9 levers, XT V's front and Avid's SD25 rear.

I am putting new cables (inner and Outer) on tonight, Is there another way of vastly improving performance,

PS. I dont mind spending a bit of cash if required, if it's worth it.

Ta
Dave

The type of blocks used can make a big difference. Softer ones will work better than the harder types but won't last anywhere near as long.

From personal experience Shimano pads are nearly useless in the wet. I'd recommend something like KoolStops or WTB pads.

You could get cartridge type blocks, where the rubber bit sits in a metal carrier; you slide out the pads when you need to replace them, rather than faffing about with allen keys...
I use BBB V brake cartridges - £10 for a set of cartridges, £6 for a set of replacement pads (from Chevin Cycles in Otley - www.chevincycles.com). They do the job, last about 3 or 4 12mile rides at this time of year.

I actually found the Shimano M-system pads that came on a set of acera V's better than the ones that came with my Deore v's when i replaced the acera when i broke one of the springs' so yes look at the blocks', Try cleaning your rims with isopropol alcohol oir methalated (spl) spirit.
Also check that your pivots aren't flexing squeeze the brakes and look for any sideways deflection if they flex get a brake booster which looks like a horse shoe and bolts on top of the v's calliper with a set of spacers

Planet X stick pads are very good! i know someone thats got them. They are about £10

I had a look at the levers last night, they seem a little stiff to pull back but very loose up and down, probably dosn't affect performance though.

I'll pop down the LBS today and see if they have any pads.

propably a silly question - but have you tried adjusting the dial on the levers - this can have a big effect on the feel of the brakes.

Also as a bit of a bodge - if you flip the tension springs off the back of the v-brakes and bend them back slightly this can makes the brakes feel 'snappier'.