Notebook – input/keypress lagging when writing in code cell

[KimTutein]

I was wondering if any of you experience lag when writing code in notebook. Not the execution of the notebook but simply writing the code. Sometimes we see seconds lag when writing code og copy/paste stuff into code cell which is very frustrating and makes for a very bad user experience (which notebooks do not deserve – I love having them in Fabric).

I have tried to disable auto-save of notebook but that did not help.

Any guidance would be highly appreciated.

Friendly regards

Kim Tutein

[KimTutein]

Hi @ObungiNiels 

Thank you for your input – it is much appreciated.

I have tried removing all output as I indeed use display alle over. This particular notebook is an ad-hoc notebook for all kinds of small code snippets and markdown cells (just with headings so I can easily navigate. It had close 200 cells (150 code cells but a lot of then just small small test with now output). After I removed all output it may be a little bit faster but not much – even a small delay when you are writing is very annoying as some times you write a few words and then wait for it to display. I then tried moving all markdown cells to see if that had any impact – it did not.

If I take a blank notebook the issues does not seem to be there - my guess it might be the number of cells might be the problem?

(by the way – my pc. has 32 gb ram and is running about 50-70% memory most of the time)

[ObungiNiels]

Hi @KimTutein ,

I agree. I can remember that I had constant performance issues in one particular notebook of mine which included very lengthy transformations with a lot of cells. Limiting the number of cells and sepearating your code into two notebooks might help with the performance. 

I reckon it makes sense to check if you can find some sort of logical partitions in your notebook and possibly split it up into multiple items. You could group those notebooks in a folder within your workspace to maintain order. 

Kind regards,

Niels

[ObungiNiels · Accepted solution]

Adding on this, I just stumbled upon this page with the limiations on notebooks: https://learn.microsoft.com/en-us/fabric/data-engineering/notebook-limitation

It mentions 256 cells maximum per notebook, so your running close to the upper boundary, which could indicate that your reaching the limit of what's possible within a single notebook item. 🙂 

[ObungiNiels]

Hi @KimTutein ,

I did experience some latency when writing code from time to time as well. At some point I noticed that this tends to occur, when I already have a lot of cells with outputs, especially with 

display(df)

in my code. 

When you revisit your notebooks, is it possible that you make lots of use of displays etc.? Especially the display function is way more than just a print out, since it offers functionalities like exploring the data with charts and using the Data Wrangler. So it is essentially a small UI which offers interactive funtionalities to the user. On the flipside, this can block memory while running the notebook and will consequently slow down the experience. 

If you have extensive outputs in your notebook, consider clearing them by navigating to Edit --> Clear all output(s). Additionally, I like to define a variable such as 

is_debug_mode = False

if is_debug_mode:
   display(df)

and relate all outputs to this variable. Then, if I need to see a data frame, I will set the variable to True before running the cell. 

Kindly try and let me know if this helped you resolve your performance issues.

If you do not have a lot of outputs in your notebooks, it would be interesting to learn more about the overall structure of your code.

Kind regards,

Niels