...it clearly needs to be updated...
Is it running slowly, or is upgrading needed because you cannot install the latest software versions? The latter means a newer computer; "slow" can sometimes be helped by those of us here with a lot of Mac experience.
Obviously we can neither see nor remotely access you computer in this setting, but there is a tool that lets us spot many known causes of slowdowns. Fortunately it is a safe and secure option.
If you want a data-driven assessment in this community, please post an EtreCheck report. We can quickly and within the limitations of these forums help you determine what issues are at play without our playing a protracted game of "20 Questions" with you that could go on for days.
EtreCheck Pro is available here: https://etrecheck.com/index
The free version will do nicely for this purpose, although the app is worthy of our financial support.
We can see hard data about drive performance, software issues and interferences, and RAM usage. Etrecheck is the development of a long-serving and trusted ASC contributor. It is a reporting app, not a "fix-it” app, expressly for displaying information in these forums to help us remotely offer suggestions for actio on your part. It will not reveal any personal or secure information.
Please see this excellent user tip on how to post long text reports like EtreCheck's into a forum response:
How to use the Add Text Feature When Post… - Apple Community
Please post the entire report. What seems insignificant to a new Etrecheck user can speak volumes to those of us who have reviewed thousands of those reports.