Yes Odoo is suitable for large-scale/public take Odoo's own website as an example Odoo now has more than 7m users around the globe. But of course it depends on your resources and where are you running Odoo. If you have the right configurations the up time of Odoo will be great.

As for the rest of your question is Odoo suitable for building a social network?
Well it depends on your technical skills to drive Odoo as framework and use it's internal ORM system to build your website. You must but in your mind that you have to make everything optimized from SQL queries to functions.

If you have your own dedicated server here is an example for the configurations:

    * Worker number calculation

        - Rule of thumb : (#CPU * 2) + 1.

        - Cron workers need CPU.

        - 1 worker ~= 6 concurrent users.

    * Memory size calculation

        - We consider 20% of the requests are heavy requests, while 80% are simpler ones.

        - A heavy worker, when all computed field are well designed, SQL requests are well designed, … is estimated to consume around 1GB of RAM.
        - A lighter worker, in the same scenario, is estimated to consume around 150MB of RAM.

    * Needed RAM = #worker * ( (light_worker_ratio * light_worker_ram_estimation) + (heavy_worker_ratio * heavy_worker_ram_estimation) )


Configuration sample

• Server with 4 CPU, 8 Thread

• 60 concurrent users

• 60 users / 6 = 10

• (4 * 2) + 1 = 9

• We’ll use 8 workers + 1 for cron. We’ll also use a monitoring system to measure cpu load, and check if it’s between 7 and 7.5 .

• RAM = 9 * ((0.8*150) + (0.2*1024)) ~= 3Go RAM for Odoo

in /etc/odoo.conf:

[options]
limit_memory_hard = 1677721600
limit_memory_soft = 629145600
limit_request = 8192
limit_time_cpu = 600
limit_time_real = 1200
max_cron_threads = 1
workers = 8

or If you need an already configured server check Odoo's own hosting services that is called Odoo.sh and you can estimate the resources you need. They have Odoo SharedHosting and Odoo DedicatedHosting plans.

We are partners with Odoo and i can provide you with an offer if you want feel free to reach.