DP 7.24 runs in 32bit and, as such, is limited to 4g RAM. There are ways around that for certain plugins. 64bit applications are not so limited.It must be DP's ability to access more RAM
Some 32bit plugs do not like any OS after 10.4, others 10.5, 10.6 with Rosetta. With a few exceptions, if a plugin ran in 10.7, it will run in a 32bit app in Yosemite. Again, there are exceptions.
When you update to 64bit DP 8, you may find that, if you get 32Lives, certain plugs may come back to life in your 64bit app. Weird but true.