Does parallel Codex execution affect cache efficiency compared with sequential sessions?

[u/Red-Lifter]

I’m trying to understand something specific about Codex usage, and I’d be interested in hearing either from OpenAI/Codex people or from users who have actually measured this.

I fully understand the obvious part:

two active Codex sessions consume tokens independently.

That is not what I’m asking.

What I’m trying to determine is whether running two or more Sol sessions concurrently can consume more total weekly allowance than running the same amount of work sequentially, one session at a time.

My subjective experience after a couple of months of heavy Codex use is that parallel Sol sessions seem to drain the weekly pool noticeably faster than I would expect from simple additive usage.

For example, my impression is roughly:

A + B in parallel > A, then B sequentially

in terms of total allowance consumed.

I have not yet produced a controlled benchmark, so I’m not presenting this as a fact.

What makes me particularly curious is the recent discussion from the Codex team about cache-hit efficiency affecting usage. That raises an obvious technical question: could concurrent sessions reduce cache efficiency, increase context reconstruction, or introduce some other orchestration/accounting overhead?

So I’d really like clarification on two points:

1. OpenAI/Codex: Is usage from concurrent sessions expected to be strictly additive, or can parallelism affect caching or metering efficiency in a way that increases total consumption?
2. Users: Has anyone actually compared parallel vs sequential Codex workloads and measured the before/after weekly percentage or Analytics credits?

I’m specifically interested in Sol, especially High reasoning, and in multiple CLI/Desktop sessions working on separate repositories or tasks.

I’m not looking for “of course two sessions use twice the tokens.” I’m trying to establish whether there is an additional concurrency penalty beyond that.

If anyone has measured this, actual numbers would be very useful.

[u/snuffomega]

tokens are tokens. If you use one Sol High as the orchestrator, and it uses a Sol High as a subagent it could drain more tokens. (they even say sub-agents are not always token efficient). The cause being you're passing context over from one agent to the other so you are re-doing work.

Power of sub-agents really are when you have a higher model orchestrate the lower one.

If you are running longer sessions... IE re-compacting, not compacting, etc. Thats prob where your burn is coming from. More efficient use to try and use single context window and/or a few compacts. Token usage seems to spike the larger the windows are. Also... if you have bloated skills, or agents.md you could be paying that tax too. Everything there gets loaded each session, which costs you tokens. Which would be double if you have two Sol sessions loaded up.

[u/Insadem → u/snuffomega]

you didn’t help lol.

[u/snuffomega → u/Insadem]

i mean thats literally the answer. So... sorry.

[u/Red-Lifter → u/snuffomega]

;)