hansva opened a new issue, #9344:
URL: https://github.com/apache/hop/issues/9344

   ### Apache Hop version?
   
   2.20.0
   
   ### Java version?
   
   21
   
   ### Operating system
   
   Other
   
   ### What happened?
   
   With **Pass all rows** enabled, the Blocking transform is much slower than 
it should be, both when it keeps the rows in memory and when it writes them to 
temporary files.
   
   **Kept in memory:** each time a row is sent on, all the rows still waiting 
are moved up one place in the list. The more rows the cache holds, the slower 
every row gets. 500,000 rows reach about 42,000 rows/s, and almost all of the 
time goes into moving the list.
   
   **Written to temporary files:** every value is compressed on its own instead 
of in larger blocks. With 1,000,000 rows and the default cache this reaches 
about 104,000 rows/s, and more than half of the time goes into compression.
   
   **Fix**
   
   - Read the rows in memory in order, without moving the list around.
   - Write and read the temporary files in blocks.
   
   
   ### Issue Priority
   
   Priority: 2
   
   ### Issue Component
   
   Component: Transforms


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