Irys uses Bundling to help Arweave scale.
Uploading large numbers of files to Arweave can be technically challenging due to Arweave's limit of 1000 transactions per block. When demand spikes, that drives up fees, making permanent data unaffordable for many users. To address these challenges, bundlers are used to collate transactions into a single bundle and submit them to Arweave.
These transactions are instantly retrievable and available to be queried. It is not necessary to wait for uploads to be confirmed and seeded on Arweave before they appear in query results.
The implementation of bundlers and bundles has helped stabilize feeds on Arweave.