Analysis Process??

The difference between PERFORMANCE and NORMAL Concurrent Analysis Process Mode is the number of tracks analyzed at one time.  Performance mode will analyze as many files as your CPU can handle while Normal mode is a bit more conservative usually only requiring about half the CPU usage.

Normal: Suitable for analysis of tracks which have a
relatively consistent.

Dynamic: Suitable for analysis of tracks which contain
significant tempo changes.

As you said ,you playing old school music. Me too.
Normal analyzing doesn't change yours BPM while playing track.
Dynamic analyzing changing yours BPM. That means If you playing song ,started with house 128 bpm if is there  in the middle of the song part of hip hop 100 BPM you will see this change,and if you using sync your second deck 2 will be cloned as deck 1.,same BPM 
But I think your major problem is beat grid. Lots of old school music has many changes in beatgrid. In each part of song is different.I hope you understand what I mean .

Hi thanks for quick respond.

Seems your answers differ however. @dubrvko Mine is set to normal but it does exactly what you're mentioning already so it's all about CPU. I think you're talking about 'Track Analysis'? This is set to dynamic and does a pretty ok job! However, most of the tracks i'm finetuning myself by grid... pfffjew

Here is mine configuration,works awesome. Especially for old school music..italo disco , 80's,etc...

@Dubrvko > You explained the difference between Normal and Dynamic Track Analysis Modes.  (Top Arrow)

I explained the differences between PERFORMANCE and NORMAL Concurrent Analysis Process Mode.  (Bottom Arrow)

Tnx Mark   

Yes you right Sorry. I have missed the word .But anyway. I just wanna say that Rekordbox is great Dj software. So far I have no any issues, everything works good with my DDJ-SX.

Best regards!