Actually any 68k machine is slow at any computing-intensive task, so we do not use any of them because they are fast. The Performa 600 is just slow by comparison with the faster machines that were shipping at the time. But it is also faster than a good many other ones (e.g., the older IIcx, or the contemporary Classic II), and because it was your first computer (mine too), why not get it going again?
Anyway, when running something like Word 5.1 or ClarisWorks 3, a Performa 600 did just fine. 68030 games played well on it, too. I wrote three books on a Performa 600 in Word 5.1, and it kept up with my typing and other requirements without complaint. Oddly enough, it did not seem limiting to me at the time. I do recall thinking how fast an LC475 was when I occasionally got to use one in the mid-90s, but I worked no faster on it, and for many purposes I can work no faster today on my G5s or MacBook Pro, than I did on that Performa 600. I certainly did more work on it than on any of the subsequent machines I have owned, as I used it right down to 2000.
A PS taken from anything from the IIci to the 7100 will work in a Performa 600; as the 7100 was the last of that series, a 7100 PS might be the one to look for (less chance of rot?). If you happen to come across one, a IIvx logic board is essentially the same as the Performa 600's, except that it has a soldered 32k L2 cache onboard, and cache is not to be sniffed at in these old machines (maybe 20% improvement?). Pop in a bigger/ faster scsi drive (ideally something like a 500MB IBM), and add 4x4MB SIMMs for 20MB of RAM (which would have been outrageously good back in the day), and you have made it a much better machine already. A faster CD drive will make a big difference, too — the Performa 600 shipped with a very basic 2x drive. An 8x or 12x SCSI CD drive will make a whale of a difference (I notice a huge difference in my Quadras with 12x SCSI CD drives), but you can go farther and get a 24x CD or even a SCSI burner, which would have been unthinkable back when the machine was new.
Almost no Nubus video card is as fast as the built-in video of a late-series Quadra, so Nubus video cards were actually intended for the most part for such slower 68030 machines. Therefore, a good Nubus video card really will genuinely accelerate a Performa 600 — unlike something like a Quadra 650, in which Nubus video is more or less pointless. This is not least because the built-in video of the Performa 600 really was basic, even by 1992 standards. You will then want a Nubus ethernet card, methinks. The third Nubus slot is the more difficult one. Add a second video card for a dual monitor setup, which we would all have drooled over in 1993, which is when I bought mine, remaindered and discounted, or a Storm DSP card for working with images (again, they were really meant for 68030-era machines and make the most dramatic difference in them rather than in 040 hardware), or get really outrageous and stick in a Radius Rocket or a PC card with a 286 processor — then you have two computers in one.
The next possibility is the PDS slot, though I'd be inclined to leave it empty even if I did get the old gal going. While physically the same as a IIci's, it will not take a IIci cache card — which is a shame, as that might otherwise have been a worthwhile thing to pop in there. I remember that there were 040 and 601 accelerators made specifically for the machine, but finding them these days is very hard. I also tend to think that the sheer slowness of the CPU is part of the charm of the machine.
Of course, tinkering with any and all this stuff is more or less pointless anyway — except that the point sometimes is just to spend some quality time with an old friend.
Having said all that, I have several 68k machines, and my Performa 600 is one of the ones in storage. But as you will perhaps gather, I have thought similarly about bringing it out and doing something with it.
I could provide some of this stuff in a single package if you want to send me a PM — only note that I will be away for the next month.
Anyway, when running something like Word 5.1 or ClarisWorks 3, a Performa 600 did just fine. 68030 games played well on it, too. I wrote three books on a Performa 600 in Word 5.1, and it kept up with my typing and other requirements without complaint. Oddly enough, it did not seem limiting to me at the time. I do recall thinking how fast an LC475 was when I occasionally got to use one in the mid-90s, but I worked no faster on it, and for many purposes I can work no faster today on my G5s or MacBook Pro, than I did on that Performa 600. I certainly did more work on it than on any of the subsequent machines I have owned, as I used it right down to 2000.
A PS taken from anything from the IIci to the 7100 will work in a Performa 600; as the 7100 was the last of that series, a 7100 PS might be the one to look for (less chance of rot?). If you happen to come across one, a IIvx logic board is essentially the same as the Performa 600's, except that it has a soldered 32k L2 cache onboard, and cache is not to be sniffed at in these old machines (maybe 20% improvement?). Pop in a bigger/ faster scsi drive (ideally something like a 500MB IBM), and add 4x4MB SIMMs for 20MB of RAM (which would have been outrageously good back in the day), and you have made it a much better machine already. A faster CD drive will make a big difference, too — the Performa 600 shipped with a very basic 2x drive. An 8x or 12x SCSI CD drive will make a whale of a difference (I notice a huge difference in my Quadras with 12x SCSI CD drives), but you can go farther and get a 24x CD or even a SCSI burner, which would have been unthinkable back when the machine was new.
Almost no Nubus video card is as fast as the built-in video of a late-series Quadra, so Nubus video cards were actually intended for the most part for such slower 68030 machines. Therefore, a good Nubus video card really will genuinely accelerate a Performa 600 — unlike something like a Quadra 650, in which Nubus video is more or less pointless. This is not least because the built-in video of the Performa 600 really was basic, even by 1992 standards. You will then want a Nubus ethernet card, methinks. The third Nubus slot is the more difficult one. Add a second video card for a dual monitor setup, which we would all have drooled over in 1993, which is when I bought mine, remaindered and discounted, or a Storm DSP card for working with images (again, they were really meant for 68030-era machines and make the most dramatic difference in them rather than in 040 hardware), or get really outrageous and stick in a Radius Rocket or a PC card with a 286 processor — then you have two computers in one.
The next possibility is the PDS slot, though I'd be inclined to leave it empty even if I did get the old gal going. While physically the same as a IIci's, it will not take a IIci cache card — which is a shame, as that might otherwise have been a worthwhile thing to pop in there. I remember that there were 040 and 601 accelerators made specifically for the machine, but finding them these days is very hard. I also tend to think that the sheer slowness of the CPU is part of the charm of the machine.
Of course, tinkering with any and all this stuff is more or less pointless anyway — except that the point sometimes is just to spend some quality time with an old friend.
Having said all that, I have several 68k machines, and my Performa 600 is one of the ones in storage. But as you will perhaps gather, I have thought similarly about bringing it out and doing something with it.
I could provide some of this stuff in a single package if you want to send me a PM — only note that I will be away for the next month.