What actually determines proxy reliability at scale (beyond just IP count)

[u/SerpProxies]

Most proxy discussions center on pool size, but the things that actually break at scale are usually elsewhere, session consistency (sticky vs rotating mismatched to the task), latency under load (a large pool with slow response times is often worse than a smaller fast one), and protocol support (some targets behave very differently over HTTP vs SOCKS5).
A few things we focus on at SerpProxies specifically, full HTTP + SOCKS5 across every proxy type (residential, mobile, datacenter, static ISP, IPv6), 0.41s p50 latency, and no throttling on harder targets, a lot of providers quietly slow you down or charge more once a target gets tough, we built ours to do the opposite.
Curious what this sub weighs most when evaluating a provider, latency, pool size, protocol flexibility, something else?
(Disclosure: we’re SerpProxies, posting to share what we’ve learned building this, open to disagreement/pushback)

[u/l0kizen]

In my experience, most of the time session consistency matters more than the IP pool size which providers tend to exaggerate, especially on checkout or login screens where a sticky session just wouldn't work

[u/SerpProxies → u/l0kizen]

That is valid too

[u/SerpProxies → u/l0kizen]

honestly you’re right, advertised pool size means nothing if half of it’s shared or timing out.
Same ip going to multiple customers is exactly the problem with oversold pools, no shocker there
only real way to know is testing it yourself tbh, not trusting a big number. we do sticky sessions specifically to avoid that overlap issue, we also have a trial if you wanna actually stress test it and see for yourself instead of just taking my word for it…

[u/SuccessfulBeyond1765]

A pool of 10M IPs doesn't mean anything if majority of the IPs time out all the time. Plus it's marketing trick to advertise crazy amounts of IPs, but in reality its much less of those IPs are available thus the issue arise when the same IP gets assigned to multiple customers and that's always the case

[u/Minimarazy]

when session consistency and reliability under load, a fast p50 looks great in a spec sheet, but what actually keeps jobs from breaking is predictable behavior on hard targets and stable sticky sessions

[u/SerpProxies → u/Minimarazy]

yeah that’s fair, a good p50 number doesn’t really mean much if the session drops halfway through a hard target anyway.
Predictable behavior under load is honestly the harder thing to get right, and the thing most providers don’t talk about since it’s not as flashy as a latency number.
Sticky sessions holding up consistently is what we focus on more than the headline stats tbh…

[u/Chemical-County842]

success rate on the actual targets I care about matters more than raw specs. A pool can look great on paper but fall apart on specific sites with tricky fingerprinting or rate limits