Artifactory's REST API does not limit the size of artifact uploads.
* For an on-prem installations, Reverse proxy or Load Balancer limit could apply: if you wish to upload large sized artifacts please make sure that you increase the connection timeout for any network elements that may participate in this. - Consult JFrog Support or the relevant documentation to determine how to do this.
If you are using Artifactory as a SaaS service in the cloud, by default you have an 8GB File Upload Max Size.
Uploading a large file should not cause any performance side-effect in Artifactory directly, although as with any data-movement, it will have some impact on your network's bandwidth. Having said that - high concurrency or rapid and heavy, e.g. metadata calculation operations, could cause some additional latency with this.