Is a slow home page better than a loading bar?

I am working on a small site which needs to load a large amount of data to show on the home page.

The page container loads fast (~1 second) but then I need to retrieve data from a database and perform calculations on it and display it in a table.

I do this via Ajax calls, but it slows the use of the page down until this completes. If you scroll, the scrolling is jumpy, etc.

Should I allow the user full access to the page after 1 second, but for the next 10 seconds the page is a big slow and laggy to use?

Or should I just display a pop-up with a loading bar and block them using the page until the page is fully ready and responsive?

Once the home page loads, the site runs really fast and all is good.