Industrial simulation: these days the optimal approach is to get access to CPU is to crunch on headless servers, ideally in the cloud. Expand and contract computing power on a needs basis.
Front-office development: Objective C and Interface Builder was much better for prototyping ideas than C. Modern python/perl/racket/go/c#/etc are much further ahead. There were no mainstream dynamic programming tools more powerful than awk when NeXT was launched. Now the most common expression of hackers is dynamic programming on fabulously powerful free tools. High-quality operating systems are also free. Documentation is free. And it's all far better than what people used to pay for.
Deployment: interactive user interfaces are now delivered through the a web browser. Previously a lot of workstations were sold to run custom internal apps.
Save your money! Get a digital ocean account, and run your macbook until the power supply dies. Perhaps in another ten years google-style web-browser laptops will be ubiquitous.