In 2013, APMdigest published a list called 15 Top Factors That Impact Application Performance. Even today, this is one of the most popular pieces of content on the site. And for good reason – the whole concept of Application Performance Management (APM) starts with identifying the factors that impact application performance, and then doing something about it.

However, in the fast moving world of IT, many aspects of application performance have changed in the 3 years since the list was published. And many new experts have come on the scene. So APMdigest is updating the list for 2016, and you will be surprised how much it has changed. Many of the basic factors are still there, and may always be. But many new factors have made the list as well. That is why the number of factors on the list has doubled, and the list will be posted in 5 parts over this week and next week.

What does this list prove? Part of the reason APMdigest posts lists of quotes from experts is so that you can read these opinions and then decide for yourself. But one point stands out clearly: there are many diverse factors that impact application performance, and this makes APM – and the other related tools such as ITOA, EUEM and NPM – even more critical today than they were when the original list was published.

As usual with the lists published on APMdigest, many of the factors listed overlap each other, just as they do in the real world. The goal of the list is not to produce a clean, definitive catalog of all the factors that can impact application performance, but rather to provide the big picture of just how many different challenges applications face today.

If you look at the list as a whole, these factors that impact application performance fall into one of two major groups: factors that are part of the environment, or factors within the app itself. Understanding where these factors come from is the first step in solving these issues.

As Kieran Taylor, Sr. Director, Product & Solutions Marketing, APM & DevOps, CA Technologies, explained, "Issues in application performance are most frequently either in the application code or underlying infrastructure services. With new microservices application architectures that span on-premises and cloud, reaching through APIs to the back end, the top factor impacting application performance is being able to clearly see the end to end picture of your application – from the user experience, app performance and even through mainframe and cloud services. Having the ability to simplify and streamline the end to end view of your applications lets you see just what you need to see to pinpoint bottlenecks before they impact users."

Part 1, the first installment of the list covers the complex environment that applications must function in today.

1. COMPLEXITY OF INFRASTRUCTURE

The top factor that impacts application performance is the complexity of the underlying infrastructure and services that supports the application. These components and services now can span multiple locations – cloud, on-premises data center, hybrid.
Payal Chakravarty
Sr. Product Manager - APM, IBM

The source factor in the environment is the complexity of new architectures to accommodate cloud, mobility and IoT.
Gabe Lowy
Technology Analyst and Founder of TechTonics Advisors

Outside of code errors, performance issues invariably stem from the point at which the application interfaces with an external system. The container, VM, storage or network. With so many layers of abstraction it's somewhat tempting for a developer to assume the system will be optimized for them.
Richard Whitehead
Chief Evangelist, Moogsoft

Digital services must now be delivered at scale and high speed of change within very complex infrastructures that can include hybrid clouds and software-defined networks. As a result, application service delivery can experience problems anywhere along the path, from the edge to the backend servers. Things can go wrong with web, application and database servers residing on various VMs and on different hypervisors as well as load balancers, network enablers, and more. In a digital enterprise where there is no off, IT teams can expect more critical errors, failed transactions, and retransmissions. Avoiding these digital minefields and reducing business risk requires removing application performance blind spots.
Ron Lifton
Senior Enterprise Solutions Marketing Manager, NetScout

2. CLOUD

One of the greatest factors impacting application performance is the decision to host an application in the cloud. The first, and often most overlooked, point of disruption is whether IT is even aware of the service migration to the cloud in the first place. All too often we see locally-hosted applications and services like VoIP or CRM platforms shift to the cloud based upon a decision made by a line of business owner. The second challenge is with managing of performance. According to respondents in the most recent Viavi State of the Network study, 90 percent cited lack of visibility and control of resources in the cloud as their largest challenge. IT needs to look more broadly at strategies for seamlessly ensuring user experience and managing application performance traversing between on-premise resources and the public cloud.
Douglas Roberts
VP and General Manager, Viavi Enterprise and Cloud Business Unit

The leading factor impacting application performance in the modern, digital era is application and infrastructure composition in the cloud. Modern apps are complex with many moving parts that play different roles in application performance – some are steady, some "burst" for seconds and then fade away. This creates a tremendous amount of dependency and when all the parts of the modern application don't perform their individual role, at the precise time they're supposed to, errors and latency are sure to ensue. The modern application and infrastructure stack, comprised of elastic architectures, microservices and service oriented architectures, challenge everything we thought we knew about guaranteeing application performance.
Shayne Higdon
VP Strategy, Vice President, Product Manaagement and Marketing for Performance & Availability, BMC Software

3. THIRD PARTY SERVICES

More than any other factor, the impact of third party elements impacts application performance. This problem is especially onerous for enterprise web sites, where every page may have dozens of tags, widgets, ads, plugins, and other third party components. Any one of them can slow down the entire site. Furthermore, even beyond websites, third party elements can impact mobile apps, SaaS apps, and any other modern application.
Jason Bloomberg
President, Intellyx

Applications are increasingly depending on 3rd party services which often leaves little control to the application owner. As microservices-based application architecture becomes more relevant, the dependencies of the application become significantly more distributed and dynamic. If a single cog in the wheel fails, the whole system may stop working, resulting in slow downs, user frustration and loss in revenue.
Payal Chakravarty
Sr. Product Manager - APM, IBM

One of the top contributing factors impacting performance of these apps is the large number of third-parties that they have to connect with. In fact, 3rd party components account for 2/3 of app experiences. With this increase in third parties comes an increase in complexity and risk for errors, poor availability and slow response times.
Rich Bentley
Senior Director of Product Marketing, Dynatrace

In our view, external third-party services and plug-ins are the most common source of performance problems. This was evidenced during the 2015 holidays – most of the performance challenges we tracked on mobile retail sites were a direct result of third-party services. Today, there is hardly a website, mobile site or application that doesn't involve some kind of third-party service integration. Examples include a growing range of specialty tools – marketing analytics, social media plug-ins and ecommerce storefronts, to name a few. The problem is that if the performance of any single one of these services degrades, it can drag down performance for an entire site or application. Organizations must be able to discern the overall performance impact of third-party services, both before and during implementation. You may rethink the latest so-called "must have" consumer feature, if it is ultimately going to slow your site way down and drive users away. Also, there must be contingency plans in place to remove and possibly replace any services that may be misbehaving.
Mehdi Daoudi
CEO and Founder, Catchpoint

4. MOBILE

Third-party resources – particularly on mobile. The numbers from a recent Google study tell the story: more than half of all page views across the Internet take place on mobile devices, yet the average load time for a page via 3G is 19 seconds. Almost half of all server requests come third-party calls, such as ads, and measuring and managing the performance of these calls is crucial. Comparing faster sites (which loaded in 5s) with slower sites (19s), the faster sites had average session lengths that were 70% longer, bounce rates that were 35% lower, and earned almost double the revenue.
Tammy Everts
Senior Researcher & Evangelist, SOASTA

5. INTERDEPENDENCIES

Today's applications and services consist of an assortment of components from multiple vendors (web and application servers, multiple tiers of middleware, databases, big data stores, caching layers, cloud, and other services) that need to function in the expected way to provide a great end-user experience. This increase in the complexity of the application and its supporting components also increases the application's chance of failing. IT operations teams and developers need to focus on gaining a holistic view into the performance of the application and not just the performance of individual components. They also need to be aware of the interdependencies between the application components in dynamic environments to ensure high availability and optimal performance of applications.
Arun Balachandran
Market Analyst, ManageEngine

The simple answer is … there is no simple answer. The complexity of distributed application architectures makes it challenging to pinpoint performance issues. Applications rely upon a vast number of unexpected dependencies and interactions with infrastructure resources. Microservices, containers, cloud infrastructure … even a minor firewall update can bring down an entire application. And many applications today are mashups of other applications that must all talk to each other for the service to execute properly. One retail website I had exposure to consisted of 80 different applications integrated into a single experience for the customer! If any portion of the mashup failed, the collective online experience failed. This is why application discovery and dependency mapping – especially in heterogeneous environments – is critical, along with the need for fulll-stack infrastructure monitoring. IT infrastructures have become increasingly fragile and it's never the same point of failure every time.
Antonio Piraino
CTO, ScienceLogic

Read Top Factors That Impact Application Performance 2016 - Part 2 covering more challenges in the environment, including containers, microservices and issues with the network.