The aim of the study is to quantitatively assess the execution time consistency of UI in distributed systems to identify invariant risk profiles and degradation mechanisms and justify consistency-first, event-aware orchestration . The methodology integrates baseline-profiling, latency-, offline-replay- and concurrency-induction with event-level  telemetry, replication and non-parametric inference. The purpose is causal isolation of the degradation mechanisms for execution time consistency of UI in distributed systems. It is empirically established that the execution time consistency of UI in distributed client systems is an infrastructure invariant that systematically degrades under perturbations. Median shifts of ≈+6%, +9% and +13% ΔSDR  were recorded, respectively, with large effect sizes (r≈0.57–1.00) for latency, offline→replay, and concurrency. A stable risk profile of UI components was identified. It was maintained in 65–85% of cases regardless of the type of failures and was explained by confirmation delays, merge conflicts, and causal/order violations. Statistical verification confirmed the significance of all effects (p<0.01 after Holm–Bonferroni) with non-overlapping 95% bootstrap CIs, which indicates generalized non-artifact degradation and justifies the necessity of event/state-aware orchestration. Further research prospects are the expansion of domains and multi-tenant architectures, the integration of causal tracing and idempotency auditing, and the combination of infrastructure and UX metrics to reduce ΔSDR ≥30% in distributed scenarios.