what is the source of your slowness? do you know exactly what to draw all the time? maybe you just need better directions. and maybe you get distracted a lot.

I think there are many factors playing a slowness in my drafting. We use BIM and sometimes it's a question what the level of detail needs to be. I think a big part may be asking questions. There are many times I am drawing and I question what I am drawing. This usually results from me looking at old drawings where I see discrepancies between what is drawn and what is noted. For example a hallway being noted as 4ft wide, but when measured using a scale it does not match the noted dimension, but I need to trace based of what is drawn because the drawings we have are old rehab drawings not originals and lack dimensions. A lot of times surveys are old and missing dimensions as well. Another thing is I don't get to go on site visits to take photos of the existing conditions, and on that subject we have not been on site to measure. This isn't school so I know the accuracy of these plans are important and I am left doubting myself often along the process. This is what I refer to when I say that it might be me having to ask more questions sooner, rather than later.

I've been working for a little over 4 years and have overseen many interns/younger staff. People who I've worked with who are slow generally because 1) they get distracted often, 2) they spend too much time including detailed information on drawings where it will never be seen, and/or 3) they don't know how to use commands and insist on using buttons. 

Not your fault, just bring up any inconsistency you find and explain the situation. It's very easy to say you need to draw faster when you're the one who is trying to solve a tricky and messy situation. Are there others in the team who do the same job as you and how do they get on? If they are fast and accurate, well you might have to speed up, learn keyboard short cuts or whatever, or just ask that colleague how they do it. But it sounds to me that you have a very difficult and time consuming task. Let them know that if they want precision and quality it takes time, or they should put an extra person on that part of the project with you if people are waiting to continue. It's also not your fault if your supervisors don't know how to budget time and distribute team members for different phases of the project.

I am fresh graduate...Now my question is that how to make connection in market with clients

everyone is slow starting out.  You are learning how to use your tools and how to be an architect.  That said you should never do a rehab without a site visit. And as a rule a second at DD once you know what you're doing.  If your job is just a draftsman then mark up everything you question and make the people responsible/doing the site visits sort ot out.

Drafting as built conditions is tricky. Even when you measure things accurately most methods have little control over the angle of measurement. Things in the real world are NEVER straight. As most people draft they put down one line and work their way clockwise or in some logical order. This tends to compound the degree or error in the measurements. At the end you end up with large discrepancies and can end up spending a lot of time trying to diagnose the problem. 

I would recommend thinking about your process. Start by drawing the longest overall measurements that you have. These are the most accurate. Then work down to smaller details. Know and allow yourself a degree of accuracy. 1/4-1/2" typically for rehab work. Each time you draw a line or wall place a dimension that corresponds to the measurement that was taken. this allows you to better diagnose problems and maintain your degree of accuracy. It also allows you to clearly see the measurements that are missing from the field or where your angular float may be. 

Beyond that: Key commands, Rhythm, Write your own shortcuts. Slowly increase your pointer mouse sensitivity, Use multiple screens to have the largest drawing space possible. Work smart, recognize symmetries and repeated conditions that can be blocks, groups or families.   

are Computerised Site Surveys not used in USA to acquire Wall Enclosures , Opes , Levels , Beams , Ridges etc ? your Firm should appointing Consultant / be billing the Client for this basic document  ? 

In software development the UI is designed with various ways of interacting with the software functionality. To become faster you tap the shortest methods to use the software and you practice techniques that save a click. A click here and there or use of shortcuts and the proper machine save hours in a week in efficiency. Mouse speed was my trick to increase speed because shortcuts and keyboard based use was secondary to me. The fastest guys I have ever seen were shortcut knowledgeable and fast with the mouse in any program they learned and in Windows as you spend some time navigating and the shortcuts which seem insignificant are NOT, find the fastest way to do everything and always do that and the keyboard has much power as does fast mouse.

Research it, then practice it, and like anything else speed comes with applied practice. Keyboard driven shortcuts and mouse speed as well as customizing menus to make your workflow seamless and intuitive for how YOU work.

And don't feel too bad, architects are generally 17 years behind technology, expect miracles as they are slowing down in comparison to the technology every hour of every day of every year the whole time, they are nobody's judge when it comes to technology.

So, that being said, always look for deeper customization opportunities and automation tools for time wasting processes.

Rehab is tough- measured drawings are never perfect, even if you made them, you never take enough pictures at the site, and the thing you really need to see will always be just outside of a photo you did take. Practice makes perfect, and you get better in time, even with just understanding the project more to set your mental filter for what needs the accuracy, and what can just ride...

work till midnight if you have to.  we're all just slaves.  that said, be patient, you will get faster.  definitely should go to the site to field measure, otherwise may as well be playing video games.