# \[Performance\] Improve build speed in bndtools by using -compression: STORE
**URL:** https://bnd.discourse.group/t/performance-improve-build-speed-in-bndtools-by-using-compression-store/502
**Category:** TIPS
**Created:** [March 2, 2025, 9:03am UTC](https://bnd.discourse.group/t/performance-improve-build-speed-in-bndtools-by-using-compression-store/502 "2025-03-02T09:03:08Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@chrisrueger](https://bnd.discourse.group/u/chrisrueger)
#### Post date: [March 2, 2025, 9:03am UTC](https://bnd.discourse.group/t/performance-improve-build-speed-in-bndtools-by-using-compression-store/502/1 "2025-03-02T09:03:08Z")
As you know bnd always produces a .jar file per bundle as its build output, and .jar files are actually zip files. And zip files can be used with and **without** compression.
I just found a simple way to speed up performance of builds, by using the [-compression](https://bnd.bndtools.org/instructions/compression.html) instruction to disable compression.
This can be used to control whether the `.jar` files bnd produces are compressed or not.
- DEFLATE: (default) compression is enabled
- STORE: no compression
Using STORE for no compression saves CPU cycles needed to compress the files.
I have now put the following into our `cnf/build.bnd`:
`-compression: ${if;${driver;eclipse};STORE;DEFLATE}`
This means that in Eclipse IDE when you are developing you will use `STORE` (no compression = faster, but bigger files). In all other builds (e.g. Maven, Gradle, Tycho etc. you will use `DEFLATE` (compressed, slower, smaller files). It uses the [${if} macro](https://bnd.bndtools.org/macros/if.html) and the [${driver} macro](https://bnd.bndtools.org/macros/driver.html).
The idea behind this tuning is my assumption , that locally in Eclipse you do not care about compression and thus larger files are acceptable, but instead you want things to be fast.
## Impact
I did some poor mans measurements to give you an impression:
### Full Workspace refresh
Doing a full workspace refresh rebuilds everything in your workspace:
`-compression: DEFLATE`: 70 seconds (avg)
`-compression: STORE`: 57s seconds (avg)
STORE was around 16-19% faster.
### web-templates bundle
This bundle contains little java code, but lots of files (web templates, images etc.) which are copied to the .jar file.
I did 3 runs.
**DEFLATE:**
```auto
filesize: 9.459.121 bytes
BUILD FULL web-templates 1 file was built in 1.257 sec
BUILD FULL web-templates 1 file was built in 1.304 sec
BUILD FULL web-templates 1 file was built in 1.252 sec
```
**STORE:**
```auto
filesize: 28.791.742 bytes
BUILD FULL web-templates 1 file was built in 0.576 sec
BUILD FULL web-templates 1 file was built in 0.611 sec
BUILD FULL web-templates 1 file was built in 0.611 sec
```
STORE is \> 50% faster.
### core-services bundle
This bundle contains a lot of java files, but little other files.
**DEFLATE**
```auto
BUILD FULL core-services 1 file was built in 5.317 sec
BUILD FULL core-services 1 file was built in 5.446 sec
BUILD FULL core-services 1 file was built in 5.610 sec
```
**STORE**
```auto
BUILD FULL core-services 1 file was built in 4.687 sec
BUILD FULL core-services 1 file was built in 4.687 sec
BUILD FULL core-services 1 file was built in 4.736 sec
```
STORE is about 12% faster.
## Conclusion
I think this is a reasonable speed up in build performance during developing OSGi bundles in the IDE with bndtools / bnd, where waiting time matters a lot, while filesize often is not that important.
Of course, it depends a little bit on the size of your workspace and the contents of your bundle. But I think this is a reasonable little trick to feel better pressing `Cmd + s` and drink less coffee 🙂
---
### Author:  [@juergen-albert](https://bnd.discourse.group/u/juergen-albert)
#### Post date: [March 3, 2025, 3:51pm UTC](https://bnd.discourse.group/t/performance-improve-build-speed-in-bndtools-by-using-compression-store/502/2 "2025-03-03T15:51:32Z")
Nice, thanks heaps for that nugget! I’ll definitely give it a try.
---
### Author:  [@chrisrueger](https://bnd.discourse.group/u/chrisrueger)
#### Post date: [May 4, 2025, 8:56am UTC](https://bnd.discourse.group/t/performance-improve-build-speed-in-bndtools-by-using-compression-store/502/3 "2025-05-04T08:56:16Z")
Another little tweak is to ensure the following in `cnf/build.bnd` is set to avoid that source files are added the jar in `OSGI-OPT` folder:
`-sources: false`
Then the copying of the sources does not happen which saves time.
Docs: [-sources BOOLEAN | bnd](https://bnd.bndtools.org/instructions/sources.html)
You could use the same conditional if/else logic above to only exclude sources during development in eclipse, but include them in the CI build.