Last updated: August 24, 2026
No, SSL does not noticeably slow down most modern websites. HTTPS adds a small amount of work when establishing a secure connection, but technologies such as TLS 1.3, HTTP/2 and HTTP/3 have made that overhead minimal. In many real-world situations, an HTTPS website can perform just as well as or better than an equivalent HTTP site.
What TLS actually costs
A TLS 1.2 handshake needed two round trips on top of the TCP handshake. TLS 1.3 cut that to one, and to zero on session resumption via 0-RTT. Over HTTP/3, QUIC folds the transport and crypto handshakes together — one round trip on first connection, zero on resumption.
The CPU cost is close to irrelevant on modern hardware. Google’s engineering team, when it moved Gmail to HTTPS by default, reported TLS accounting for under 1% of CPU load, under 10KB of memory per connection, and under 2% of network overhead — and that was before AES-NI became universal. No extra machines, no crypto accelerators.
Why HTTPS usually ends up faster
The honest comparison isn’t HTTPS vs HTTP. It’s HTTP/2 or HTTP/3 over TLS vs HTTP/1.1 in the clear. HTTP/1.1 caps you at roughly six connections per origin with head-of-line blocking and uncompressed headers on every request. Multiplexing and HPACK/QPACK recover far more time than one handshake round trip costs. Protocol choice is only one input to perceived speed — Core Web Vitals measure what users actually feel.
Why did my website become slower after installing SSL?
The certificate is almost never the cause. Check these in order:
- Redirect chains — http:// to https:// to https://www is two extra round trips on every cold visit. Collapse to one hop and add HSTS (ideally preloaded) to remove it entirely.
- Mixed content — subresources still on http:// get blocked or upgraded, and blocked assets can stall rendering for seconds.
- HTTP/2 not actually enabled — plenty of stacks terminate TLS and still serve 1.1. Confirm in DevTools, Network tab, Protocol column.
- Session resumption off — forces a full handshake per connection.
- TLS terminated at origin, not at the edge — round-trip cost scales with distance. Terminate at a CDN PoP — most managed WordPress hosts bundle this.
- Certificate chain length — every extra intermediate is more bytes in the first flight.
How to measure it
WebPageTest’s waterfall breaks out the SSL negotiation segment per request — that is the number to argue about, not a synthetic score. SSL Labs will confirm your TLS version, cipher suites and resumption config.
Does SSL affect SEO?
HTTPS is also recommended for SEO and page experience. Google strongly recommends websites use HTTPS and generally prefers the HTTPS version of a page when both HTTP and HTTPS versions are available. However, HTTPS alone will not suddenly improve your rankings. Content quality, relevance and the overall page experience remain much more important.
If slow loading times persist after your HTTPS setup has been checked, the issue may lie elsewhere in your website’s configuration, hosting or optimisation. Regular website maintenance and performance optimisation can help identify these issues before they affect users.
Find out more about what an SSL certificate actually does in our article.
