Individual tags or aliases? No. Lots of elements (INTs, DINTs, REALs, etc) packed into arrays or structures that can be read in bulk with no gaps? Probably. Or very close. Try creating four arrays of 5000 DINTs each in your processor, and subscribing them in Ignition by themselves. (Disable all your other tags.) See what you get.
BTW, if a connection path in Rockwell products supports buffer sizes above the default, they’ll generally support a buffer of 4000. There’s no point using 1500. Consider also switching from a time slice-based comms allocation to fixed periodic pacing of your PLC’s tasks. Eliminating the continuous task in a PLC (or converting it to periodic) generally yields better comms processing without sacrificing necessary logic latency.