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Leonid Kuznetsov

Service · Frontend Modernization & Performance

Make your frontend platform fast, reliable, and cheap to change again.

Frontend platforms decay quietly: renders get slower, bundles get heavier, every feature takes longer than the last, and nobody can say exactly why. I diagnose these systems with a profiler rather than opinions, and I fix them incrementally — because for a product with real users, a rewrite is usually the most expensive option on the table.

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Sound familiar?

The situations this service exists for.

  • Pages feel slow, and complaints are rising, but profiling data is nobody’s job
  • Every change breaks something unrelated; senior engineers are afraid of whole areas of the codebase
  • Bundle size, memory leaks, or rendering cost are hurting real user metrics
  • A rewrite has been proposed — and you suspect it’s the wrong call, but need evidence

Scope

What the work covers.

  • Profiling-driven diagnosis: React rendering, memory, bundle and runtime cost, data loading
  • Architecture review of state management, module boundaries, and typed contracts
  • Fixes for the critical user flows first — measured before and after
  • Incremental modernization plans that don’t stop feature delivery
  • Testing and observability so regressions get caught before users find them

Outcomes

What you end up with.

  • A measured, prioritized picture of where performance actually goes
  • Critical flows made demonstrably faster and more reliable
  • A modernization path your team executes in normal sprints — no big-bang rewrite

Engagement formats

How to buy this.

Technical Strategy Session

60–90 minutes

A paid working session on one defined problem: an architecture choice, an AI feature plan, a performance question, a build-vs-buy call. You bring the context; I bring pattern recognition from 13+ years of shipping in situations like yours.

Start here →

Product & Architecture Diagnostic

3–5 days

A focused investigation of one high-impact problem. I read the code, profile the system, interview the people closest to the pain, and separate symptoms from causes.

Start here →

Implementation or Rescue Sprint

2–4 weeks, fixed scope

I take hands-on ownership of the most critical part of the work — writing production code, making the blocking decisions, and coordinating with your product, design, and backend people until it ships.

Start here →

Entry product

React Performance Diagnostic

The lowest-risk way to start: a focused, fixed-scope investigation that produces findings your team can act on — whether or not we work together afterwards. Scoped after a fit call.

  • Production-realistic profiling
  • Critical-flow measurements
  • Rendering, memory, network, and bundle findings
  • Ranked remediation plan
  • Measurement framework your team keeps
  • Team walkthrough
Request diagnostic scope →

Fit

This is a fit when…

  • A React/TypeScript product with real users is slow, fragile, or expensive to change
  • A rewrite is on the table and you want evidence before betting the roadmap
  • You want fixes measured on the flows users actually complain about

Not a fit

This is not a fit when…

  • You want a big-bang rewrite executed without diagnosis
  • There is no access to production-realistic data or environments
  • Generic staff augmentation is what you actually need

FAQ

Common questions.

Do you implement the fixes or just report?

Both are available: the diagnostic produces the ranked plan; a delivery sprint takes hands-on ownership of the highest-impact fixes.

Will delivery stop during modernization?

No — the approach is incremental by design. Changes ship in normal release cycles along seams the diagnostic identifies.

Evidence

Related work.

Tell me what is blocked, underperforming, or difficult to ship.

I will tell you whether I can help — and what the smallest useful next step would be. If I’m not the right person, I’ll say so.

Start a conversationor email js.leonid.kuznetsov@gmail.com