Apache Gzip level adjustment

Gzip level does impact our performance, because itself is a conflicting stuff—-consuming CPU% to reduce the file size in order to reduce the long duration network time.

so we need take these three things into consideration:
1.Network speed
2.Apache http Server capacity,especially CPU
3.File Compression ratio(.js, .Css, .html,.xml)

I did a quick testing charts based on different Gzip level and high speed Network:

Chart1—response time under different Gzip level
Gzip level | response time | Apache CPU%
Level 9 | 0.85s | 98%
Level 7 | 0.60s | 97%
Level 6 | 0.53s | 96%
Level 5 | 0.45s | 95%
Level 3 | 0.42s | 93%
Level 2 | 0.40s | 93%
Level 1 | 0.38s | 93%

Chart2—X.js Compression ratio under different Gzip level
orginal size of X.js=140K

Gzip level | After compression size
Level 9 | 30.1K
Level 7 | 30.1K
Level 6 | 30.3K
level 5 | 31.2K
Level 4 | 33K

I choose:
DeflateCompressionLevel 6

so from testing result, we can see level 9 is not always right :) just for your reference, make your own Gzip level.