that for some God-given reason, radioactive decay went faster in the past
I won't bother with finding the sites unless someone really wants to but:
There is a creationist site that actually sites specific scientific papers about difference in the rate of radioactive decay. They talk about "bound state beta decay" and another condition which causes very significant changes in the rate of change of nucluli. This is, of course, used to support the suppostition that dating of rocks could be wrong because decay rates can TOO change.
Unfortunately for the credibility of this source it leaves out a couple of facts. I would say that leaving them out makes it dishonest but perhaps that is in the mind of the beholder.
Bound state beta decay (only one of the ways for something to decay) requires complete or nearly complete ionization of the atom in question. This is not mentioned (odd that) nor are the conditions required to produce this mentioned. Not mention is made of the chances of the rocks of the earth being in a plasma state anytime during the past 4 Gyrs made.
The other change does mention the conditions --- I don't remember the exact numbers -- something like 200 million degress if I remember right. That fact that this might apply to a supernova and not even the core of the sun seems to have gotten left out. Something of an oversight perhaps?