Spinoff from SOLR-3684.
Most lucene tokenizers have some buffer size, e.g. in CharTokenizer/ICUTokenizer its char.
But the jflex tokenizers use char by default, which seems overkill. I'm not sure we really see any performance bonus by having such a huge buffer size as a default.
There is a jflex parameter to set this: I think we should consider reducing it.
In a configuration like solr, tokenizers are reused per-thread-per-field,
so these can easily stack up in RAM.
Additionally CharFilters are not reused so the configuration in e.g.
HtmlStripCharFilter might not be great since its per-document garbage.