starting with 123d design: weird pixels and laggy

Hnnn you should have way more than enough computer to run  123design . the only thing i see is your screen resolution is set pretty high it may be showing/ causing the anomalies the screen shot on this machine looks fine but my resolution is much lower about half. 
So you can ignore them and try the program or maybe tone down your screen resolution.
Hope this helps.

Good to here you were able to sort out the issue .
I think you will like this program .
I find it very intuitive but sometimes it can be frustrating.
Feel free to post any question you you may have.

Settings in German so you from Germany   ??
Sometime a huge help to post location.

I would recommend tinkercad for beginners to start with 3d modelling. 

Pros:
1. It very intuitive and less chance of get frustrated.
2. Your model are stored online and can be accessed indepent of which computer you are using.
3. It is web based so no need to install anything.

Cons:
1. It only provide limited functions but more than enough for beginner. I get all I needed done in tinkercad.
2. May become slower when object become very complex, that is usually not a problem for beginners.

https://www.tinkercad.com/

I couldn't agree more.

I only recommend it for beginners. it is easy to learn and easy to use.

I don't know where you guys get your computer science degree, but I was tough cloud based computing is evolutionary. Cloud based computing and Personal computing both has its own Pros and Cons, why you guys always have to pick one side? I always choose to take advantage of both selectively.

I agree with the major flaw, nothing is perfect. Personal computer also have one major flaw, if the hard drive malfunction, you lost your data. That's why I think they both have pros and cons, And that's why I use them in combination.

As the technology evolves, there will be more backup server and connection choices, if my wifi at home breakdown, I can access my file use cell phone, and cloud based network will have more backup servers, and personal computer can afford to have hard drive arrays for backup.

which cloud you referring to?

Is facebook and social media markets classified as cloud? Who will post property file on social media? I always encrypt property file before sync with One Drive or Google Drive just for safety reasons.

So better option is to run social media website on your personal computer?

if I don't let them "to make copies of, retain, transmit, reformat, display, and distribute via communication tools Your Content on the Services", it is illegal for them to sync my files between my computers or share with co-workers. And I clearly don't have to decrypt  my file so that they can appear in demonstrations or materials that promote the Service

I think you would be right, Bozotclown1970.. LOL

I do not use "cloud services" unless I absolutely need to, and then only long enough to upload from one device and download to another. I do not leave things in the cloud for the very reasons outlined in the user agreement shown above.
I do not need my phone and my computer to be synchronized, either... =/

I do not use cloud based programs for the simple fact that my internet service is not reliable enough. I live in a very rural area, we do not have access to cable, or even DSL, internet services. About the only real drawback to living out here.

A smart person learns how to make back-ups of their data, so even in the event of a hard drive crash, they still have their stuff.. external drives have gotten rather cheap with lots of space, so easy enough to buy one or two and back things up. I have a couple of 1TB drives that I use, and thinking about getting another one.

you are quite welcome. but not really necessary to thank me.

I honestly do not like the whole cloud thing, and find it amazing that people do not understand the risks involved and what they are agreeing to in using those services. It is stunning to think that people just simply click "OK" without actually reading anything.

In the example you provided I find this particularly troubling...

...you grant to Microsoft a worldwide and royalty-free intellectual property license to use Your Content,...

and...

...Your Content may appear in demonstrations or materials that promote the Service...

Meaning they can use your content however they see fit, without compensating you for that use.
Sorry, but NO.

And yes, Facebook and other social media sites have similar language in their user agreements, so by posting pictures on FB, Twitter, etc - you are agreeing to the potential use of your stuff, whether you like it or not.