OK. This is not my idea, but I certainly don't remember who posted it.
AI's do swap tech at a prodigious rate that humans cannot equal because they are simply a piece of code that instructs them to check other countries and if those other countries posses techs that they don't have, swap for it. The AI's are always on. Humans, well we get sloppy now and again don't we? This problem is not even exclusive to Victoria. Galactic Civilizations II has the same issue and for the very same reason. Fortunately, GCII has a switch to turn off all tech trading.
Anyway, on to the idea. You gain a new tech. Pause the game. Check the Great Powers. Start with the UK. Does your new tech show up as being tradeable? Great! You have a leg up. Trade it for another tech. Do not unpause the game. Go to the next GP and trade with them. You can go negative on research points if you like, although I very seldom take down to below a -10. You can play it as you desire, but it seems to me that RPs recover more slowly when they drop into the negative. I do not have any data to support this notion.
Any way, so long as the game is paused, the other countries are not trading your newly researched technology. But just as soon as you unpause, them little AI codes are going to go to work and that first AI you traded with is going to start trading away, and those countries will start trading and suddenly you have critical mass and then EVERYONE has the new tech, and you have nothing.
Don't have excess RP's, try and use the new tech plus some money from your treasury to trade land for tech or something.
Anyway, this trick works much better in the late game when you have a lot of excess research points, assuming you do have excess. Sometimes I don't. A smaller European country like Belgium or the Netherlands is almost always guaranteed to have excess RP's by late game, however. Brazil or Peru, maybe not so much. Still it's not impossible.