That's a good point. PostScript needs floating point numbers and lots of memory. At one point in history, for the typical "Desktop Publishing" setup of a Mac and a LaserWriter, the LaserWriter actually had more CPU power and memory than the Mac!
>The LaserWriter used the same Canon CX printing engine as the HP LaserJet, and as a consequence early LaserWriters and LaserJets shared the same toner cartridges and paper trays. PostScript is a complete programming language that has to be run in a suitable interpreter and then sent to a software rasterizer program, all inside the printer. To support this, the LaserWriter featured a Motorola 68000 CPU running at 12 MHz, 512 kB of workspace RAM, and a 1 MB frame buffer.
>At introduction, the LaserWriter had the most processing power in Apple's product line—more than the 8 MHz Macintosh. As a result, the LaserWriter was also one of Apple's most expensive offerings. For implementation purposes, the LaserWriter employed a small number of medium-scale-integration Monolithic Memories PALs, and no custom LSI, whereas the LaserJet employed a large number small-scale-integration Texas Instruments 74-Series gates, and one custom LSI. The LaserWriter was, thereby, in the same form factor (for its RIP), able to provide much greater function, and, indeed, much greater performance, all within the very same LBP-CX form factor, although the external packaging was, for marketing purposes, somewhat different.
... and the LaserWriter's 68000 wasn't even top of the line for custom RIPs. I worked at a company in Seattle in the early 1990s that had a custom RIP engine based on the Motorola but faster, with more memory and better connectivity to the CPU. I don't remember it's name - I just had to write the device driver for Interactive Linux to make it work :)
https://en.wikipedia.org/wiki/LaserWriter#Hardware
>The LaserWriter used the same Canon CX printing engine as the HP LaserJet, and as a consequence early LaserWriters and LaserJets shared the same toner cartridges and paper trays. PostScript is a complete programming language that has to be run in a suitable interpreter and then sent to a software rasterizer program, all inside the printer. To support this, the LaserWriter featured a Motorola 68000 CPU running at 12 MHz, 512 kB of workspace RAM, and a 1 MB frame buffer.
>At introduction, the LaserWriter had the most processing power in Apple's product line—more than the 8 MHz Macintosh. As a result, the LaserWriter was also one of Apple's most expensive offerings. For implementation purposes, the LaserWriter employed a small number of medium-scale-integration Monolithic Memories PALs, and no custom LSI, whereas the LaserJet employed a large number small-scale-integration Texas Instruments 74-Series gates, and one custom LSI. The LaserWriter was, thereby, in the same form factor (for its RIP), able to provide much greater function, and, indeed, much greater performance, all within the very same LBP-CX form factor, although the external packaging was, for marketing purposes, somewhat different.