Performance testing has always been technically demanding, but modern web applications add a new layer of difficulty. Features designed for security and user experience can make realistic load simulation genuinely hard. Here are the challenges that most often trip teams up.
Multi-factor authentication (MFA)
MFA requires a second factor — a code from an app, SMS, or hardware key — that a script cannot easily reproduce. Teams usually work around it by using test accounts with MFA relaxed in the test environment, or by scripting against a controlled second-factor mechanism.
Token timeout and expiry
Modern apps use access tokens that expire quickly. In a long-running performance test, tokens can time out mid-run, causing a flood of false failures unless the script refreshes them correctly.
Correlation of dynamic values
Applications constantly pass dynamic values — session ids, CSRF tokens, view states — between requests. Scripts must capture these from responses and feed them into later requests (correlation). Miss one, and the virtual users stop behaving like real ones.
Pop-ups and dynamic UI
Cookie banners, consent pop-ups, and heavily dynamic single-page interfaces complicate scripting, especially for protocol-level tools that do not run a real browser.
Single sign-on (SSO)
SSO redirects users through an external identity provider, adding extra steps and tokens that must be handled carefully in scripts — and sometimes coordinated with a third party you do not control.
Modern challenges layered on a request
Conclusion
MFA, token timeouts, correlation, pop-ups, and SSO make performance testing of modern web applications considerably harder than it used to be. Anticipating these challenges — and planning the environment, accounts, and scripting to handle them — is what separates a realistic performance test from a misleading one.