Thousands of patients were waiting for routine treatment at Southern Health in August, figures show.
The figures come as a leading health charity says the NHS is grappling with "really serious challenges", as typical winter pressures are to be made worse by the cost-of-living crisis and Covid-19.
NHS England figures show 4,726 patients were waiting for non-urgent elective operations or treatment at Southern Health NHS Foundation Trust at the end of August – up from 4,508 in July, and 3,793 in August 2021.
None of those had been waiting for longer than a year.
The median waiting time from referral at an NHS Trust to treatment at Southern Health was eight weeks at the end of August – up from seven weeks in July.
Nationally, 7 million people were waiting to start treatment at the end of August.
Siva Anandaciva, chief analyst at the King's Fund, a health charity, said the NHS is struggling with "crumbling buildings and outdated equipment, long waiting lists for care, high levels of Covid-19 and growing staff shortages."
"Successive governments’ refusal to confront the worsening health and care workforce crisis and their chronic underinvestment in NHS buildings and infrastructure has created this mix of problems.
"This winter, typical seasonal pressures on NHS services will be amplified by Covid-19 and a cost-of-living crisis that could impact on people’s physical and mental health," she added.
Separate figures show 1.5 million patients in England were waiting for a key diagnostic test in August – the same as in July.
At Southern Health, 1,558 patients were waiting for one of nine standard tests, such as an MRI scan, non-obstetric ultrasound or gastroscopy at this time.
Of them, 15 (1%) had been waiting for at least six weeks.
NHS Providers, which acts on behalf of health organisations in England, said the level of pressure across the health system "remains concerning".
It pointed to recent news of a shortage in blood supplies as creating delays for non-urgent operations.
A Department of Health and Social Care spokesperson said: “This level of performance is not what patients expect and we must do better for them.
"The Deputy Prime Minister has set out her ABCD priorities – easing pressures on ambulances, clearing the Covid backlogs, supporting the care sector so patients can leave hospital and improving access to doctors and dentists.
“The public can support the NHS this winter by getting their flu jabs and Covid booster vaccines if eligible.”