Whitebox, BaFin-Regulated Robo-Advisory Platform
Whitebox — BaFin-regulated robo-advisory platform
4.7★
App Store rating
−40%
P95 API latency
50k+
AUM users impacted
0
Compliance regressions
Overview
Slow portfolio loads were eroding user trust in a BaFin-regulated wealth app. We restructured the iOS networking layer, cutting P95 latency 40% with zero compliance regressions.
The challenge
What we were up against
Whitebox serves over 50,000 users with assets under management in a BaFin-regulated environment. Portfolio load times had climbed to 3.2 seconds at P95, triggering negative App Store reviews and a spike in support tickets. Users managing investment portfolios interpret slowness as instability, and in regulated fintech that perception directly impacts retention. The backend team had already optimized their API responses. The bottleneck sat entirely on the iOS side: redundant serial requests, no request coalescing, and JSON parsing blocking the main thread.
The approach
Engineering decisions
Profiled the full request lifecycle with Instruments Network profiler and Charles Proxy to establish a baseline and pinpoint the serial request chains causing the worst delays.
Refactored portfolio and transaction data fetching from sequential URLSession calls to parallel async/await groups using Swift Concurrency, cutting wait times on dependent data loads.
Moved JSON decoding off the main thread with a dedicated decoding actor, eliminating UI frame drops that made the app feel unresponsive during data refresh.
Implemented response caching with ETags and conditional GET requests, reducing redundant full-payload responses by 60% on repeat visits and saving bandwidth costs.
Added MetricKit instrumentation to track P50, P90, and P95 latency in production, giving the team regression detection before users notice a slowdown.
The outcome
Results
P95 API latency dropped 40% in the first release cycle, bringing portfolio load times from 3.2s down to 1.9s on a standard 4G connection. Support tickets related to slow loading fell sharply the following quarter. The app maintained its 4.7-star App Store rating throughout the transition. Zero compliance regressions: every change passed BaFin data-handling review before shipping.
4.7★
App Store rating
−40%
P95 API latency
50k+
AUM users impacted
0
Compliance regressions
Tech stack