11×

normal traffic on the first day of term

0

failed logins during enrolment week

-62%

lesson page load time on mobile

5

weeks of load testing before term

The problem

Tessera sells online courses to schools and adult learners, and most of its traffic arrives in three short windows a year. On the old host, the first morning of term meant thousands of students logging in at once, sessions timing out, and teachers emailing support instead of teaching.

They had tried a bigger server, but paying for term-start capacity all year cost more than the rest of their infrastructure combined.

What we did

1

Replayed last year’s term-start logs against a staging copy to find where it actually broke: session writes and quiz autosave, not page views.

2

Moved sessions and quiz autosave out of the database into an in-memory store, and cached course pages for logged-out visitors.

3

Scheduled auto-scale to add vCPU and RAM ahead of each known term date, then step back down two weeks later.

4

Ran a load test at twelve times normal traffic every week for five weeks before term, fixing one bottleneck each round.

Where it landed

Enrolment week peaked at eleven times a normal day and logins never failed. Lesson pages load 62% faster on mobile, where most students study, and the extra capacity is only paid for during the weeks it is used.

Tessera is on Pro with scheduled scaling, and the load test now runs as a standing check every August.

At a glance

Sector

Online education

Scale

180,000 learners, three term peaks a year

Regions

London, Singapore

Plan

Pro, with auto-scale

Timeline

Five weeks, zero downtime