It has great package management with https://www.quicklisp.org/beta/ and some truly great and high quality libraries, especially Fukamachi's suite of web libraries and so many others. Woo, for example, is the fastest web server. https://github.com/fukamachi/woo (Faster then the runner up Go by quite a bit)
For parallel computing, we use: https://lparallel.org/ Its been great at handling massive loads accross all processors elegantly. And then for locking against overwrites on highly parallel database transactions we use mutex locks that are built into the http://sbcl.org/ compiler with very handy macros.
Slightly off-topic but I'm in awe of Fukamachi's repos. That one person has built so much incredible stuff is amazing to me. Not sure it's enough to get me using CL all the time, but it's very impressive.
The only gaps we've had with our production code and lisp is PDF (we use the java pdfbox), translating between RDF formats (also a java lib) and encrypting JWP tokens for PKCE dPop authentication (also java)
The complete conceputal AI system and space/time causal systems digital twin technology is all in common lisp (sbcl)
Also fantastic is the sb-profile library in sbcl that lets you profile any number of functions and see number of iterations and time used as well as consing all ordered by slowest cummulative time. That feature has been key on finding those functions that are slow and optimizing leading to orders of magnitude speed improvements.
We basically build a space/time model of the world, where systems are performing functions in events that take input states and change them into output states such that those events either causally trigger each other or the causal link that the input states to an event means that the event outputting that states is the cause of the current event.
The conceptual AI models operational concepts based on an understanding on how human concepts work, inference and automatic classification using those concepts, and then learning new concepts. The operational side of the digital twin uses functional specifications held elsewhere, which is also true of the operational concepts which use specifications in the form of conceptual definitions.
And the technology takes in RDF graph as data for input, builds the digital twin model from that data with extensive infererence, then expresses itself back out with RDF graph data. (Making https://solidproject.org/ the ideal protocol for us where each pod is a digital-twin of something)
We are working toward commercial launch in the coming weeks. (We are adding Project Pods, Business Pods, Site Pods with harvesting the sematic parse we do of PDFs into the pod, so we handle very big data)
I don't really consider quicklisp to be "great package management" since you have to download it, install it, then load it. And don't forget to modify your sbcl init script to load it automatically for you. It felt quite cumbersome to get started using it, even though it was simple enough after that. Rust has truly great package management in my opinion. I run one command to install Rust and I immediately have access to all crates in crates.io.
EDIT: It's kind of ironic for me to make this claim since I use Emacs as my editor...
For parallel computing, we use: https://lparallel.org/ Its been great at handling massive loads accross all processors elegantly. And then for locking against overwrites on highly parallel database transactions we use mutex locks that are built into the http://sbcl.org/ compiler with very handy macros.