How to speed up initial translation from SVN to Git

At the average, translation of one revision takes 1-1.5 seconds. So the bigger the amount of the revision is, the longer is the translation. If it is too slow, though, there are few things to consider:

Most often, slow translation is caused by incorrect branches and tags mapping configuration. The most recommended way to create correct configuration is to use subgit configure with --layout auto option:
```
$ subgit configure --layout auto --trunk TRUNK_PATH SVN_PROJECT_URL [GIT_REPO_PATH]
```
where
- TRUNK_PATH - a path, relative to the SVN_PROJECT_URL, that leads to the directory, playing the role of ‘trunk’ or ‘mainline of development’ in the SVN project.
- SVN_PROJECT_URL - a URL that points to a single project in SVN repository, that’s intended to be translated to Git.
- GIT_REPO_PATH - an optional path to a new Git repository, where the SVN project will be translated to.
For example, the command may look like this:
```
$ subgit configure --layout auto --trunk main http://example.com/svn/repository/project /home/user/project.git
```
SubGit will connect to the SVN project, scan its history and try to find appropriate branches and tags,based on the TRUNK_PATH, and create valid mapping configuration.
In rare occasions, though, the SVN project history and layout are so complex SubGit cannot create correct mapping configuration. In these cases the only way to set the mapping scheme is to create it manually following the mapping guide.
Another reason to change the mapping scheme manually is to exclude some branches, tags or particular files from the translation if they are not worth to be translated to Git. It can also speed up the translation, as the fewer branches and tags are in a mapping, the fewer revisions and data to translate.

There are a few more configuration options that can affect translation performance:

an EOLs translation feature that tells SubGit to perform line endings translation for each file and this process may strongly affect translation performance. To improve translation performance that feature can be turned off in SubGit configuration file:
```
[translate]
    eols = false
```
It has to be set before translation start.

a stream file threshold that’s being set by the setting of the same name:
```
[core]
    streamFileThreshold = <size in bytes>
```
It changes the way SubGit works with Git blobs: loads fully to memory or streams byte-by-byte from disk. Normally full loading is faster but may result into OutOfMemoryError.

when streaming Git blobs, SubGit tries to use ‘git’ binary, that is expected to be found on the ‘gitPath’ path presented by gitPath:
```
[core]
    gitPath = /path/to/git/executable
```
If SubGit doesn’t find Git binary, it uses internal means of streaming and they may be much slower.
finally, a setting that sets Git Garbage Collector behavior:
```
[svn]
    triggerGitGC = [true|false|N]
```
by default, SubGit invokes git gc –auto with every revision and it may affect the translation performance. To speed up the translation, the GC can be either switched off (‘false’) or being invoked not so often (‘N’, a number of revisions between each invocation).

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