OneBox Load Testing

Here it is better to wait for answers from the development teams.
I will answer only what happened 3-4 years ago.
We strived not only to ensure that all pages opened in an average of 500 ms, but also that OneBox could digest huge amounts of data at the same time. Even 3-4 years ago, a completely normal situation was when OneBox holds:
- 1,000,000 items
- 10,000,000 contacts
- 5,000,000 orders (orders and tasks)
I generally keep quiet about the events, the bottom is not visible there.
For example, our OneBox in which we ourselves work now holds something about 15 million contacts and about 25 million events for them (letters, calls, etc.). This is not the total amount of infrastructure, but only one specific OneBox.
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In general, in order to substantively answer the question, it is better to understand what kind of performance indicators are of interest and at what amount of data.