When you have been using Sage50c for a few years, especially if you have a very busy business with lots of invoices, or even lots of products on each invoice, then running reports, checking your data and taking a backup can become really slow ...
But how often do you really need to run a report or check data that is a few years old? You need to keep the data for 6 years after the end of last company financial year relating to the data that they refer to, but if you don't need to run reports which cover multiple years right up to present day then you could choose to archive the old data and just keep the most recent year(s) in your active live data.
One thing that really annoys me about this process is Sage tried to label the file where the archive is stored with the year from the START of your financial year when it is common practice to talk about your year end. So, if your accounts are running from April 2019 to March 2020 I would change the reference in the Year End -> Archive option to 2020 instead of the 2019 Sage suggest.
This archive, once saved, will then be available to log into just like a separate company, with all the transactions and invoices from your company up to the date you made the archive. If you didn't take an archive as part of your year end process as you weren't sure it was needed you can go to Tools -> Period End -> Archive Company and take a company archive at any time.
This then allows you to delete old transactions, invoices and old accounts in your current data as you have the records saved in your archive!
You will need to take care that you backup the archive data safely, and also remember what the passwords were to access your company at the date of the archive, as any changes made in you company data will not ripple through into the archives.
When you update to a new version, you should also go to the File -> Open -> Company Archive area and update your archives too.
If anything I've written here resonates with you, call me on 01604 420057 and let's see how we can help you.