I've seen something like this asked many times, but I never see a clear answer given.

Given an express server with a block like this:

var express = require('express');
var router = express.Router();    

app.use(async function(req, res, next){
    console.log("REQUEST DETECTED");
    await new Promise(r => setTimeout(r, 5000));
    next();
});

app.use('/', router.get('/', function(req, res, next) {
    // Serve a basic page
});

Consider this timeline

1. Navigate a browser to the / route
2. Console logs "REQUEST DETECTED"
3. Open a new tab to the / route
4. 5 seconds later, tab 1 displays the page content and the console outputs "REQUEST DETECTED" a second time.
5. 5 seconds later, tab 2 displays the page content.

What I expected would be

1. Navigate a browser to the / route
2. Console logs "REQUEST DETECTED"
3. Open a new tab to the / route
4. Console logs "REQUEST DETECTED" a second time.
5. 5 seconds later, both tabs display the page content.

Can Express not capitalize on time spent awaiting in order to process other requests? And just to be clear, the same thing happens when I await useful work like running a DB query. If one user requests a heavy query, the entire site hangs for every other user. Is there an alternative solution here?