We have got an activity chain through different tasks and processes which fails

@mohamedb Added to other's suggestions, I would like to suggest you to go through the instance's Process details ('Process Nodes' in particular). This will give you a high level idea about the time consuming operations. This serves your purpose incase if the operations (or nodes) being carried out in the process are heavier in terms of size and time. Actually this is one of the ways we used to opt for, to find out time consuming operations which thereby leads to chain breakage.

@mohamedb Added to other's suggestions, I would like to suggest you to go through the instance's Process details ('Process Nodes' in particular). This will give you a high level idea about the time consuming operations. This serves your purpose incase if the operations (or nodes) being carried out in the process are heavier in terms of size and time. Actually this is one of the ways we used to opt for, to find out time consuming operations which thereby leads to chain breakage.