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Response time checker
Powered by Larm's global probe network. Full waterfall breakdown per location.
Understanding the waterfall
Every HTTP request goes through several phases before you see a response. When your site feels slow, the waterfall shows you exactly which phase is the bottleneck — and from which location.
DNS Lookup
Resolving the domain name to an IP address. Slow DNS usually means your DNS provider is slow from that region, or the record isn't cached at the resolver. If DNS is slow from one location but fast from others, it's likely a regional DNS propagation issue.
TCP Connect
Establishing the TCP connection (the SYN → SYN-ACK handshake). This is pure network latency between the probe and your server. If TCP is slow from distant locations but fast from nearby ones, that's expected — it's the speed of light. If it's slow from everywhere, your server might be overloaded or dropping connections.
TLS Handshake
Negotiating the encrypted connection (certificate exchange, key agreement). Typically 1-2 round trips on top of TCP. Slow TLS can indicate a large certificate chain, an overloaded server struggling with crypto, or a missing OCSP staple forcing the client to check certificate revocation separately.
Time to First Byte (TTFB)
The time between sending the request and receiving the first byte of the response. This is where your application does its work — database queries, API calls, template rendering. If TTFB is the dominant phase, the bottleneck is your server, not the network. If TTFB varies by location, you might have a CDN serving some regions from cache and others from origin.
Content Transfer
Downloading the response body. Depends on response size and bandwidth between the probe and your server. Large pages, uncompressed responses, or high-resolution images show up here. If transfer is slow but TTFB is fast, enable gzip/brotli compression or reduce the response size.
Monitor your response times continuously.
Larm uses multi-probe voting to check your services from these same locations every 30 seconds to 3 minutes. Get alerted when things slow down.
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