Performance

Performance

Titanium targets low-overhead MITM proxying: connection pooling, HTTP/2 multiplexing, and buffer reuse. Numbers below are Release measurements with RpsLoadProbe (and BenchmarkDotNet / Basic example where noted). They are orientation only — absolute RPS varies by hardware, OS, and background load.

For pooling knobs and certificate first-visit tuning, see Performance and pooling.

Measurement environment

Windows (developer laptop)

Unless a subsection names another host, saturation RPS tables used:

OS	Windows 11 (10.0.26200)
CPU	11th Gen Intel Core i7-1185G7 @ 3.00 GHz (8 logical processors)
RAM	31.8 GiB
Runtime	.NET 10.0.10
nginx	nginx/Windows 1.31.3
Harness	RpsLoadProbe Release; arms run sequentially

Linux (GitHub-hosted ubuntu-latest)

Fair TLS-terminate numbers in Linux saturation were measured on a stock Actions runner (not a container job):

OS	Ubuntu 24.04.4 LTS
CPU	AMD EPYC 7763 (4 logical processors on the VM)
RAM	15.6 GiB
Runtime	.NET 10.0.11
nginx	nginx/1.24.0 (Ubuntu)
Harness	RpsLoadProbe Release; compare-terminate (HTTP/3 arms skipped — no QuicListener / msquic on this image)

At a glance

What	Result
HTTPS TTFB vs direct (median, 14 hosts)	Cold ≈ parity (−1 ms); warm −25 ms (proxy faster)
HTTP/1 loopback GET (no body intercept)	~186 µs, ~17.5 KB allocated / request
Cleartext reverse HTTP/1 peak	~16.0k RPS (TWP) vs ~15.5k RPS (nginx/Windows)
TLS-terminate reverse HTTP/1 peak (Windows)	~21.8k RPS (TWP) vs ~14.4k RPS (nginx/Windows)
TLS-terminate H2→H1 cleartext peak (Windows)	~7.4k RPS @ c=64, 0% err (TWP) · nginx ~14.9k @ c=32
TLS-terminate H3→H1 cleartext peak (Windows)	~2.4k RPS @ c=32, 0% err (TWP)
Cross-version bridges under load (Windows)	All H1↔H2↔H3 directions 0% err — see Bridge matrix
TLS-terminate reverse HTTP/1 peak (Linux GHA)	~18–37k RPS (TWP) vs ~28–61k (nginx); TWP÷nginx ≈ 0.61 stable — see Linux vs Windows
TLS-terminate H2→H1 cleartext peak (Linux GHA)	~10–24k RPS (TWP) · nginx H2 ~19–42k peak
Explicit HTTPS MITM peak	~13.6k RPS
Basic example footprint (Release, after load)	~74 MB working set · ~24–29 MB private bytes

Why isn’t HTTP/3 > HTTP/2 > HTTP/1 in raw RPS?

For tiny JSON responses (~64 B) on loopback, that ordering is not expected:

1. Topology dominates protocol. Always compare arms that share the same crypto hop count and upstream protocol.
2. HTTP/2/3 shine at multiplexing, not at maximizing single-origin tiny-GET RPS.
3. Fair terminate topology (client TLS → cleartext origin) is what nginx uses for H2. TWP matches that with ForwardCleartext + the H2→H1 bridge (and H1 TLS terminate).

H2→H1 cleartext bridge

Under multiplexed load an earlier bridge path used RespondStreaming (HEADERS without END_STREAM + DATA). .NET HttpClient reported Received an HTTP/2 pseudo-header as a trailing header and error rates climbed with concurrency. The stream was also missing IsExternalBridge, racing Http2Helper against the synthetic emitter.

The shipped path marks IsExternalBridge, buffers the origin body, and emits via the buffered synthetic path. Keep-alive pooling remains enabled with residual-buffer and lease guards.

Saturation RPS

Reproduce locally (Release):

pwsh tools/RpsLoadProbe/run-rps.ps1 -Mode compare-terminate

Fair TLS-terminate compare (compare-terminate) — Windows

Local Release (warmup 1s / measure 4s; concurrency 8, 32, 64). Host: Windows (developer laptop). Cleartext-origin arms use process-split origin/proxy.

Arm	Topology	Sustainable	Peak	Notes
TWP H1 TLS	Client TLS → cleartext H1	21,803 @ 64	21,803	0% err
nginx H1 TLS	ssl → cleartext H1	13,826 @ 64	14,424 @ 32	0% err
TWP H2→H1	Client h2 TLS → H2→H1 bridge → cleartext H1	7,373 @ 64	7,373	0% err
nginx H2	Client h2 TLS → cleartext H1	5,898 @ 64	14,920 @ 32	0% err
TWP H3→H1	Client h3 → cleartext H1	2,327 @ 64	2,423 @ 32	0% err

Bridge matrix (compare-bridges) — Windows

Local Release compare-bridges (warmup 1s / measure 3s; concurrency 8, 32). All arms 0% error.

Arm	Client → origin	Peak @ c=32
H2→H1 cleartext	H2 TLS → H1 cleartext	9,104
H1→H2	H1 TLS → H2 TLS	8,843
H1→H3	H1 TLS → H3 QUIC	13,499
H2→H3	H2 TLS → H3 QUIC	5,055
H3→H1 cleartext	H3 → H1 cleartext	3,593
H3→H2	H3 → H2 TLS	1,842
H2↔H2 MITM	H2 TLS → H2 TLS	4,330
H3↔H3 MITM	H3 → H3	8,477

Linux vs Windows (H1 TLS)

On the Windows laptop, TWP H1 TLS leads nginx/Windows (~21.8k vs ~14.4k). On Linux GHA, nginx leads. Absolute GHA RPS swings ~2× between VMs, but the TWP÷nginx ratio stays ≈ 0.61 across runs (including after process-split, ThreadPool floors, and Server GC on the probe). The ranking flip is nginx/Windows being slow vs native Linux nginx (epoll), not a Linux-only TWP correctness bug. The residual ~40% is managed SslStream + proxy pipeline vs nginx C — not closed by harness knobs.

Fair TLS-terminate compare — Linux (GitHub-hosted ubuntu-latest)

Latest CSV: rps-ramp-20260816-082447.csv (Actions artifact rps-csv from run 31936352891 @ cbed2a40; warmup 2s / measure 8s; concurrency 8, 16, 32, 64). Host: Linux (GitHub-hosted). HTTP/3 arms skipped (no QuicListener / msquic on this image). A quieter VM earlier the same day hit ~37k / ~61k at the same ~0.61 ratio (31936116039).

Arm	Topology	Sustainable	Peak	Notes
TWP H1 TLS	Client TLS → cleartext H1	20,734 @ 64	20,734	0% err · ≈61% of nginx
nginx H1 TLS	ssl → cleartext H1	34,104 @ 64	34,104	0% err
TWP H2→H1	Client h2 TLS → H2→H1 bridge → cleartext H1	13,886 @ 64	13,886	0% err
nginx H2	Client h2 TLS → cleartext H1	16,235 @ 64	22,267 @ 32	~0% err

On the GHA VM (4 vCPU), nginx still leads peak RPS; TWP stays zero-error.

Protocol / topology matrix

Client	Upstream	TWP	nginx/Windows	Mode
H1 cleartext	H1 cleartext	yes	yes	compare
H1 TLS	H1 cleartext	ForwardCleartext	ssl proxy_pass http://	compare-terminate
H2 TLS	H1 cleartext	H2→H1 bridge + ForwardCleartext	ssl+http2 → cleartext	compare-terminate
H2 TLS	H2 TLS (MITM)	native h2↔h2	n/a (nginx terminates)	compare-tls / reverse-http2
H2 TLS	H2 cleartext (h2c)	not supported (no h2c)	uncommon	—
H3 QUIC	H3 QUIC	MITM	no QUIC on nginx/Windows	reverse-http3
H1 TLS	H2 TLS	H1→H2 bridge	—	reverse-http11-to-http2
H1 TLS	H3 QUIC	H1→H3 bridge	—	reverse-http1-to-http3
H2 TLS	H3 QUIC	H2→H3 bridge	—	reverse-http2-to-http3
H3 QUIC	H2 TLS	H3→H2 (Http2OriginConnection pool)	—	reverse-http3-to-http2
H3 QUIC	H1 cleartext	ForwardCleartext + Http11	—	reverse-http3-cleartext
All of above (matrix)				compare-bridges

Raising limits on large hosts

There is no artificial upper clamp on server defaults. Per-endpoint overrides:

Knob	Scope	Default	Override
ProxyServer.MaxCachedConnections	process, per upstream host	128	any ≥ 1
ProxyEndPoint.MaxCachedConnections	endpoint → pool depth for that EP’s sessions	null (use server)	e.g. 256 on reverse EP
ProxyEndPoint.MaxConcurrentClients	endpoint admission	null (off)	any ≥ 1
ResourceLimits.MaxConcurrentStreamsPerConnection	H2 streams	256	ProxyResourceLimits.Create(...)
TransparentQuicProxyEndPoint.MaxInboundBidirectionalStreams	H3	100 (probe uses 256)	property on EP
ForwardCleartext	transparent TLS terminate	false	true + decrypt

proxy.MaxCachedConnections = 512;
proxy.ResourceLimits = ProxyResourceLimits.Create(
    /* … */,
    maxConcurrentStreamsPerConnection: 1000,
    maxCachedConnectionsPerHost: 512,
    /* … */);

var ep = new TransparentProxyEndPoint(IPAddress.Any, 443, decryptSsl: true)
{
    ForwardHost = "127.0.0.1",
    ForwardPort = 8080,
    ForwardCleartext = true,
    MaxCachedConnections = 256, // deeper pool for this reverse EP only
    GenericCertificateName = "example.com"
};
ep.BeforeSslAuthenticate += (_, a) =>
{
    a.UpstreamHttpProtocol = UpstreamHttpProtocol.Http11;
    a.AllowHttpProtocolTranslation = true; // H2 client → H1 origin bridge
    return Task.CompletedTask;
};

HTTPS latency / loopback microbenchmarks

dotnet run -c Release --project benchmarks/Titanium.Web.Proxy.Benchmarks -- --filter '*Throughput*'

Benchmark	Setup	Mean	Allocated / op
HTTP/1 GET through proxy	Passthrough	186 µs	17.5 KB
HTTP/2 multiplexed GETs	10 concurrent streams	3.0 ms / batch	~14 KB / request

Process footprint (Basic example)

Metric	Approx. value
Working set	~74 MB
Private bytes	~24–29 MB